--- a/js/src/builtin/JSON.cpp
+++ b/js/src/builtin/JSON.cpp
@@ -7,26 +7,26 @@
 #include "builtin/JSON.h"
 
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/Range.h"
 #include "mozilla/ScopeExit.h"
 
 #include "jsarray.h"
 #include "jsnum.h"
-#include "jsstr.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
+#include "builtin/String.h"
+#include "util/StringBuffer.h"
 #include "vm/Interpreter.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/JSONParser.h"
-#include "vm/StringBuffer.h"
 
 #include "jsarrayinlines.h"
 #include "jsboolinlines.h"
 
 #include "vm/JSAtom-inl.h"
 #include "vm/NativeObject-inl.h"
 
 using namespace js;

--- a/js/src/builtin/MapObject.cpp
+++ b/js/src/builtin/MapObject.cpp
@@ -10,17 +10,17 @@
 #include "gc/FreeOp.h"
 #include "js/Utility.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/SelfHosting.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 #include "gc/Marking-inl.h"
 #include "vm/Interpreter-inl.h"
 #include "vm/NativeObject-inl.h"
 
 using namespace js;
 
 using mozilla::IsNaN;

--- a/js/src/builtin/Object.cpp
+++ b/js/src/builtin/Object.cpp
@@ -3,27 +3,26 @@
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "builtin/Object.h"
 
 #include "mozilla/MaybeOneOf.h"
 
-#include "jsstr.h"
-
 #include "builtin/Eval.h"
 #include "builtin/SelfHostingDefines.h"
+#include "builtin/String.h"
 #include "frontend/BytecodeCompiler.h"
 #include "jit/InlinableNatives.h"
 #include "js/UniquePtr.h"
+#include "util/StringBuffer.h"
 #include "vm/AsyncFunction.h"
 #include "vm/JSContext.h"
 #include "vm/RegExpObject.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/Shape-inl.h"
 #include "vm/UnboxedObject-inl.h"
 
 #ifdef FUZZING
 #include "builtin/TestingFunctions.h"

--- a/js/src/builtin/RegExp.cpp
+++ b/js/src/builtin/RegExp.cpp
@@ -7,21 +7,21 @@
 #include "builtin/RegExp.h"
 
 #include "mozilla/CheckedInt.h"
 #include "mozilla/TypeTraits.h"
 
 #include "frontend/TokenStream.h"
 #include "irregexp/RegExpParser.h"
 #include "jit/InlinableNatives.h"
+#include "util/StringBuffer.h"
+#include "util/Unicode.h"
 #include "vm/JSContext.h"
 #include "vm/RegExpStatics.h"
 #include "vm/SelfHosting.h"
-#include "vm/StringBuffer.h"
-#include "vm/Unicode.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/UnboxedObject-inl.h"
 
 using namespace js;
 using namespace js::unicode;
 

rename from js/src/jsstr.cpp
rename to js/src/builtin/String.cpp
--- a/js/src/jsstr.cpp
+++ b/js/src/builtin/String.cpp
@@ -1,15 +1,15 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/CheckedInt.h"
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/PodOperations.h"
 #include "mozilla/Range.h"
 #include "mozilla/TypeTraits.h"
@@ -31,33 +31,33 @@
 #include "builtin/RegExp.h"
 #include "jit/InlinableNatives.h"
 #include "js/Conversions.h"
 #include "js/UniquePtr.h"
 #if ENABLE_INTL_API
 # include "unicode/uchar.h"
 # include "unicode/unorm2.h"
 #endif
+#include "util/StringBuffer.h"
+#include "util/Unicode.h"
 #include "vm/BytecodeUtil.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/Opcodes.h"
 #include "vm/Printer.h"
 #include "vm/RegExpObject.h"
 #include "vm/RegExpStatics.h"
 #include "vm/SelfHosting.h"
-#include "vm/StringBuffer.h"
-#include "vm/Unicode.h"
 
 #include "vm/Interpreter-inl.h"
-#include "vm/String-inl.h"
 #include "vm/StringObject-inl.h"
+#include "vm/StringType-inl.h"
 #include "vm/TypeInference-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using JS::Symbol;
 using JS::SymbolCode;
 

rename from js/src/jsstr.h
rename to js/src/builtin/String.h
--- a/js/src/jsstr.h
+++ b/js/src/builtin/String.h
@@ -1,31 +1,31 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef jsstr_h
-#define jsstr_h
+#ifndef builtin_String_h
+#define builtin_String_h
 
 #include "mozilla/HashFunctions.h"
 #include "mozilla/PodOperations.h"
 
 #include <stdio.h>
 #include <string.h>
 
 #include "jsutil.h"
 #include "NamespaceImports.h"
 
 #include "gc/Rooting.h"
 #include "js/RootingAPI.h"
 #include "js/UniquePtr.h"
+#include "util/Unicode.h"
 #include "vm/Printer.h"
-#include "vm/Unicode.h"
 
 class JSAutoByteString;
 class JSLinearString;
 
 namespace js {
 
 class StringBuffer;
 
@@ -522,9 +522,9 @@ StringConstructor(JSContext* cx, unsigne
 extern bool
 FlatStringMatch(JSContext* cx, unsigned argc, Value* vp);
 
 extern bool
 FlatStringSearch(JSContext* cx, unsigned argc, Value* vp);
 
 } /* namespace js */
 
-#endif /* jsstr_h */
+#endif /* builtin_String_h */

rename from js/src/builtin/SymbolObject.cpp
rename to js/src/builtin/Symbol.cpp
--- a/js/src/builtin/SymbolObject.cpp
+++ b/js/src/builtin/Symbol.cpp
@@ -1,18 +1,18 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "builtin/SymbolObject.h"
+#include "builtin/Symbol.h"
 
-#include "vm/StringBuffer.h"
-#include "vm/Symbol.h"
+#include "util/StringBuffer.h"
+#include "vm/SymbolType.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 
 using JS::Symbol;
 using namespace js;
 
 const Class SymbolObject::class_ = {

rename from js/src/builtin/SymbolObject.h
rename to js/src/builtin/Symbol.h
--- a/js/src/builtin/SymbolObject.h
+++ b/js/src/builtin/Symbol.h
@@ -1,19 +1,19 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef builtin_SymbolObject_h
-#define builtin_SymbolObject_h
+#ifndef builtin_Symbol_h
+#define builtin_Symbol_h
 
 #include "vm/NativeObject.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 namespace js {
 
 class SymbolObject : public NativeObject
 {
     /* Stores this Symbol object's [[PrimitiveValue]]. */
     static const unsigned PRIMITIVE_VALUE_SLOT = 0;
 
@@ -60,9 +60,9 @@ class SymbolObject : public NativeObject
 extern JSObject*
 InitSymbolClass(JSContext* cx, HandleObject obj);
 
 extern JSObject*
 InitBareSymbolCtor(JSContext* cx, HandleObject obj);
 
 } /* namespace js */
 
-#endif /* builtin_SymbolObject_h */
+#endif /* builtin_Symbol_h */

--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -33,28 +33,28 @@
 #include "js/HashTable.h"
 #include "js/StructuredClone.h"
 #include "js/UbiNode.h"
 #include "js/UbiNodeBreadthFirst.h"
 #include "js/UbiNodeShortestPaths.h"
 #include "js/UniquePtr.h"
 #include "js/Vector.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/AsyncFunction.h"
 #include "vm/AsyncIteration.h"
 #include "vm/Debugger.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/ProxyObject.h"
 #include "vm/SavedStacks.h"
 #include "vm/Stack.h"
-#include "vm/StringBuffer.h"
 #include "vm/TraceLogging.h"
 #include "wasm/AsmJS.h"
 #include "wasm/WasmBinaryToText.h"
 #include "wasm/WasmJS.h"
 #include "wasm/WasmModule.h"
 #include "wasm/WasmSignalHandlers.h"
 #include "wasm/WasmTextToBinary.h"
 #include "wasm/WasmTypes.h"

--- a/js/src/builtin/TypedObject.cpp
+++ b/js/src/builtin/TypedObject.cpp
@@ -9,21 +9,21 @@
 #include "mozilla/Casting.h"
 #include "mozilla/CheckedInt.h"
 
 #include "jsutil.h"
 
 #include "builtin/SIMD.h"
 #include "gc/Marking.h"
 #include "js/Vector.h"
+#include "util/StringBuffer.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSFunction.h"
-#include "vm/String.h"
-#include "vm/StringBuffer.h"
+#include "vm/StringType.h"
 #include "vm/TypedArrayObject.h"
 
 #include "gc/Nursery-inl.h"
 #include "gc/StoreBuffer-inl.h"
 #include "vm/JSAtom-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/Shape-inl.h"

--- a/js/src/builtin/intl/Collator.cpp
+++ b/js/src/builtin/intl/Collator.cpp
@@ -16,17 +16,17 @@
 #include "builtin/intl/ICUStubs.h"
 #include "builtin/intl/ScopedICUObject.h"
 #include "builtin/intl/SharedIntlData.h"
 #include "gc/FreeOp.h"
 #include "js/TypeDecls.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSContext.h"
 #include "vm/Runtime.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/JSObject-inl.h"
 
 using namespace js;
 
 using js::intl::GetAvailableLocales;
 using js::intl::IcuLocale;
 using js::intl::ReportInternalError;

--- a/js/src/builtin/intl/CommonFunctions.h
+++ b/js/src/builtin/intl/CommonFunctions.h
@@ -12,17 +12,17 @@
 
 #include <stddef.h>
 #include <stdint.h>
 #include <string.h>
 
 #include "builtin/intl/ICUStubs.h"
 #include "js/RootingAPI.h"
 #include "js/Vector.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 
 namespace intl {
 
 /**
  * Initialize a new Intl.* object using the named self-hosted function.
  */

--- a/js/src/builtin/intl/IntlObject.cpp
+++ b/js/src/builtin/intl/IntlObject.cpp
@@ -20,17 +20,17 @@
 #include "builtin/intl/ICUStubs.h"
 #include "builtin/intl/NumberFormat.h"
 #include "builtin/intl/PluralRules.h"
 #include "builtin/intl/ScopedICUObject.h"
 #include "js/Class.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/JSObject-inl.h"
 
 using namespace js;
 
 using mozilla::Range;
 using mozilla::RangedPtr;
 

--- a/js/src/builtin/intl/PluralRules.cpp
+++ b/js/src/builtin/intl/PluralRules.cpp
@@ -12,17 +12,17 @@
 #include "mozilla/Casting.h"
 
 #include "builtin/intl/CommonFunctions.h"
 #include "builtin/intl/ICUStubs.h"
 #include "builtin/intl/ScopedICUObject.h"
 #include "gc/FreeOp.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSContext.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 
 using namespace js;
 
 using mozilla::AssertedCast;
 

--- a/js/src/builtin/intl/SharedIntlData.cpp
+++ b/js/src/builtin/intl/SharedIntlData.cpp
@@ -8,22 +8,21 @@
 
 #include "builtin/intl/SharedIntlData.h"
 
 #include "mozilla/Assertions.h"
 #include "mozilla/HashFunctions.h"
 
 #include <stdint.h>
 
-#include "jsstr.h"
-
 #include "builtin/intl/CommonFunctions.h"
 #include "builtin/intl/ICUStubs.h"
 #include "builtin/intl/ScopedICUObject.h"
 #include "builtin/intl/TimeZoneDataGenerated.h"
+#include "builtin/String.h"
 #include "js/Utility.h"
 #include "vm/JSAtom.h"
 
 using js::HashNumber;
 using js::intl::StringsAreEqual;
 
 template<typename Char>
 static constexpr Char

--- a/js/src/builtin/intl/SharedIntlData.h
+++ b/js/src/builtin/intl/SharedIntlData.h
@@ -12,17 +12,17 @@
 #include <stddef.h>
 
 #include "js/AllocPolicy.h"
 #include "js/CharacterEncoding.h"
 #include "js/GCAPI.h"
 #include "js/GCHashTable.h"
 #include "js/RootingAPI.h"
 #include "js/Utility.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 
 namespace intl {
 
 /**
  * Stores Intl data which can be shared across compartments (but not contexts).
  *

--- a/js/src/ctypes/CTypes.h
+++ b/js/src/ctypes/CTypes.h
@@ -12,17 +12,17 @@
 #include "ffi.h"
 #include "prlink.h"
 
 #include "ctypes/typedefs.h"
 #include "js/AllocPolicy.h"
 #include "js/GCHashTable.h"
 #include "js/UniquePtr.h"
 #include "js/Vector.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 namespace ctypes {
 
 /*******************************************************************************
 ** Utility classes
 *******************************************************************************/
 

--- a/js/src/frontend/BytecodeCompiler.h
+++ b/js/src/frontend/BytecodeCompiler.h
@@ -7,17 +7,17 @@
 #ifndef frontend_BytecodeCompiler_h
 #define frontend_BytecodeCompiler_h
 
 #include "mozilla/Maybe.h"
 
 #include "NamespaceImports.h"
 
 #include "vm/Scope.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 #include "vm/TraceLogging.h"
 
 class JSLinearString;
 
 namespace js {
 
 class LazyScript;
 class LifoAlloc;

--- a/js/src/frontend/NameFunctions.cpp
+++ b/js/src/frontend/NameFunctions.cpp
@@ -7,18 +7,18 @@
 #include "frontend/NameFunctions.h"
 
 #include "mozilla/MemoryChecking.h"
 #include "mozilla/Sprintf.h"
 
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/ParseNode.h"
 #include "frontend/SharedContext.h"
+#include "util/StringBuffer.h"
 #include "vm/JSFunction.h"
-#include "vm/StringBuffer.h"
 
 using namespace js;
 using namespace js::frontend;
 
 namespace {
 
 class NameResolver
 {

--- a/js/src/frontend/TokenStream.cpp
+++ b/js/src/frontend/TokenStream.cpp
@@ -21,22 +21,22 @@
 #include "jsexn.h"
 #include "jsnum.h"
 
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/Parser.h"
 #include "frontend/ReservedWords.h"
 #include "js/CharacterEncoding.h"
 #include "js/UniquePtr.h"
+#include "util/StringBuffer.h"
+#include "util/Unicode.h"
 #include "vm/HelperThreads.h"
 #include "vm/JSAtom.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
-#include "vm/StringBuffer.h"
-#include "vm/Unicode.h"
 
 using mozilla::ArrayLength;
 using mozilla::MakeScopeExit;
 using mozilla::PodArrayZero;
 using mozilla::PodCopy;
 
 struct ReservedWordInfo
 {

--- a/js/src/frontend/TokenStream.h
+++ b/js/src/frontend/TokenStream.h
@@ -173,21 +173,21 @@
 #include <stdio.h>
 
 #include "jspubtd.h"
 
 #include "frontend/ErrorReporter.h"
 #include "frontend/TokenKind.h"
 #include "js/UniquePtr.h"
 #include "js/Vector.h"
+#include "util/Unicode.h"
 #include "vm/ErrorReporting.h"
 #include "vm/JSContext.h"
 #include "vm/RegExpShared.h"
-#include "vm/String.h"
-#include "vm/Unicode.h"
+#include "vm/StringType.h"
 
 struct KeywordInfo;
 
 namespace js {
 namespace frontend {
 
 struct TokenPos {
     uint32_t    begin;  // Offset of the token's first char.

--- a/js/src/gc/Allocator.cpp
+++ b/js/src/gc/Allocator.cpp
@@ -8,17 +8,17 @@
 
 #include "gc/GCInternals.h"
 #include "gc/GCTrace.h"
 #include "gc/Nursery.h"
 #include "jit/JitCompartment.h"
 #include "threading/CpuCount.h"
 #include "vm/JSContext.h"
 #include "vm/Runtime.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "gc/ArenaList-inl.h"
 #include "gc/Heap-inl.h"
 #include "gc/PrivateIterators-inl.h"
 #include "vm/JSObject-inl.h"
 
 using namespace js;
 using namespace gc;

--- a/js/src/gc/AtomMarking.h
+++ b/js/src/gc/AtomMarking.h
@@ -5,17 +5,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef gc_AtomMarking_h
 #define gc_AtomMarking_h
 
 #include "NamespaceImports.h"
 #include "ds/Bitmap.h"
 #include "threading/ProtectedData.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 namespace js {
 namespace gc {
 
 class Arena;
 
 // This class manages state used for marking atoms during GCs.
 // See AtomMarking.cpp for details.

--- a/js/src/gc/Barrier.cpp
+++ b/js/src/gc/Barrier.cpp
@@ -10,17 +10,17 @@
 #include "gc/Policy.h"
 #include "gc/Zone.h"
 #include "js/HashTable.h"
 #include "js/Value.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSObject.h"
 #include "vm/SharedArrayObject.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 #include "wasm/WasmJS.h"
 
 namespace js {
 
 bool
 RuntimeFromActiveCooperatingThreadIsHeapMajorCollecting(JS::shadow::Zone* shadowZone)
 {
     MOZ_ASSERT(CurrentThreadCanAccessRuntime(shadowZone->runtimeFromActiveCooperatingThread()));

--- a/js/src/gc/GC.cpp
+++ b/js/src/gc/GC.cpp
@@ -228,31 +228,31 @@
 #include "vm/JSAtom.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Printer.h"
 #include "vm/ProxyObject.h"
 #include "vm/Shape.h"
-#include "vm/String.h"
-#include "vm/Symbol.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
 #include "vm/Time.h"
 #include "vm/TraceLogging.h"
 #include "vm/WrapperObject.h"
 
 #include "gc/Heap-inl.h"
 #include "gc/Marking-inl.h"
 #include "gc/Nursery-inl.h"
 #include "gc/PrivateIterators-inl.h"
 #include "vm/GeckoProfiler-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/JSScript-inl.h"
 #include "vm/Stack-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using mozilla::ArrayLength;
 using mozilla::Maybe;
 using mozilla::Move;
 using mozilla::Swap;

--- a/js/src/gc/Marking.cpp
+++ b/js/src/gc/Marking.cpp
@@ -22,27 +22,27 @@
 #include "vm/ArgumentsObject.h"
 #include "vm/ArrayObject.h"
 #include "vm/Debugger.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/RegExpObject.h"
 #include "vm/RegExpShared.h"
 #include "vm/Scope.h"
 #include "vm/Shape.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 #include "vm/TypedArrayObject.h"
 #include "vm/UnboxedObject.h"
 #include "wasm/WasmJS.h"
 
 #include "gc/GC-inl.h"
 #include "gc/Nursery-inl.h"
 #include "gc/PrivateIterators-inl.h"
 #include "vm/JSCompartment-inl.h"
 #include "vm/NativeObject-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 #include "vm/UnboxedObject-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using JS::MapTypeToTraceKind;
 
 using mozilla::DebugOnly;

--- a/js/src/gc/Tracer.cpp
+++ b/js/src/gc/Tracer.cpp
@@ -13,17 +13,17 @@
 
 #include "gc/GCInternals.h"
 #include "gc/Marking.h"
 #include "gc/PublicIterators.h"
 #include "gc/Zone.h"
 #include "vm/JSFunction.h"
 #include "vm/JSScript.h"
 #include "vm/Shape.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 #include "gc/GC-inl.h"
 #include "vm/JSCompartment-inl.h"
 #include "vm/ObjectGroup-inl.h"
 
 using namespace js;
 using namespace js::gc;
 using mozilla::DebugOnly;

--- a/js/src/gdb/tests/test-JSString.cpp
+++ b/js/src/gdb/tests/test-JSString.cpp
@@ -1,14 +1,14 @@
 #include "gdb-tests.h"
 
 #include "vm/JSContext.h"
 // When JSGC_ANALYSIS is #defined, Rooted<JSFlatString*> needs the definition
 // of JSFlatString in order to figure out its ThingRootKind
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 FRAGMENT(JSString, simple) {
   AutoSuppressHazardsForTest noanalysis;
 
   JS::Rooted<JSString*> empty(cx, JS_NewStringCopyN(cx, nullptr, 0));
   JS::Rooted<JSString*> x(cx, JS_NewStringCopyN(cx, "x", 1));
   JS::Rooted<JSString*> z(cx, JS_NewStringCopyZ(cx, "z"));
 

--- a/js/src/irregexp/RegExpParser.cpp
+++ b/js/src/irregexp/RegExpParser.cpp
@@ -31,18 +31,18 @@
 #include "irregexp/RegExpParser.h"
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Move.h"
 
 #include "frontend/TokenStream.h"
 #include "gc/GC.h"
 #include "irregexp/RegExpCharacters.h"
+#include "util/StringBuffer.h"
 #include "vm/ErrorReporting.h"
-#include "vm/StringBuffer.h"
 
 using namespace js;
 using namespace js::irregexp;
 
 using mozilla::Move;
 using mozilla::PointerRangeSize;
 
 // ----------------------------------------------------------------------------

--- a/js/src/jit/CodeGenerator.cpp
+++ b/js/src/jit/CodeGenerator.cpp
@@ -16,21 +16,21 @@
 #include "mozilla/ScopeExit.h"
 #include "mozilla/Unused.h"
 
 #include <type_traits>
 
 #include "jslibmath.h"
 #include "jsmath.h"
 #include "jsnum.h"
-#include "jsstr.h"
 
 #include "builtin/Eval.h"
 #include "builtin/RegExp.h"
 #include "builtin/SelfHostingDefines.h"
+#include "builtin/String.h"
 #include "builtin/TypedObject.h"
 #include "gc/Nursery.h"
 #include "irregexp/NativeRegExpMacroAssembler.h"
 #include "jit/AtomicOperations.h"
 #include "jit/BaselineCompiler.h"
 #include "jit/IonBuilder.h"
 #include "jit/IonIC.h"
 #include "jit/IonOptimizationLevels.h"
@@ -38,24 +38,24 @@
 #include "jit/JitSpewer.h"
 #include "jit/Linker.h"
 #include "jit/Lowering.h"
 #include "jit/MIRGenerator.h"
 #include "jit/MoveEmitter.h"
 #include "jit/RangeAnalysis.h"
 #include "jit/SharedICHelpers.h"
 #include "jit/StackSlotAllocator.h"
+#include "util/Unicode.h"
 #include "vm/AsyncFunction.h"
 #include "vm/AsyncIteration.h"
 #include "vm/MatchPairs.h"
 #include "vm/RegExpObject.h"
 #include "vm/RegExpStatics.h"
 #include "vm/TraceLogging.h"
 #include "vm/TypedArrayObject.h"
-#include "vm/Unicode.h"
 #include "vtune/VTuneWrapper.h"
 
 #include "jsboolinlines.h"
 
 #include "jit/MacroAssembler-inl.h"
 #include "jit/shared/CodeGenerator-shared-inl.h"
 #include "jit/shared/Lowering-shared-inl.h"
 #include "vm/Interpreter-inl.h"

--- a/js/src/jit/IonTypes.h
+++ b/js/src/jit/IonTypes.h
@@ -10,17 +10,17 @@
 #include "mozilla/HashFunctions.h"
 
 #include <algorithm>
 
 #include "jsfriendapi.h"
 #include "jstypes.h"
 
 #include "js/Value.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 namespace jit {
 
 typedef uint32_t RecoverOffset;
 typedef uint32_t SnapshotOffset;
 typedef uint32_t BailoutId;
 

--- a/js/src/jit/MCallOptimize.cpp
+++ b/js/src/jit/MCallOptimize.cpp
@@ -2,26 +2,26 @@
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/Casting.h"
 
 #include "jsmath.h"
-#include "jsstr.h"
 
 #include "builtin/AtomicsObject.h"
 #include "builtin/intl/Collator.h"
 #include "builtin/intl/DateTimeFormat.h"
 #include "builtin/intl/NumberFormat.h"
 #include "builtin/intl/PluralRules.h"
 #include "builtin/intl/RelativeTimeFormat.h"
 #include "builtin/MapObject.h"
 #include "builtin/SIMD.h"
+#include "builtin/String.h"
 #include "builtin/TestingFunctions.h"
 #include "builtin/TypedObject.h"
 #include "jit/BaselineInspector.h"
 #include "jit/InlinableNatives.h"
 #include "jit/IonBuilder.h"
 #include "jit/Lowering.h"
 #include "jit/MIR.h"
 #include "jit/MIRGraph.h"

--- a/js/src/jit/MIR.cpp
+++ b/js/src/jit/MIR.cpp
@@ -10,19 +10,19 @@
 #include "mozilla/EndianUtils.h"
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/MathAlgorithms.h"
 
 #include <ctype.h>
 
 #include "jslibmath.h"
-#include "jsstr.h"
 
 #include "builtin/RegExp.h"
+#include "builtin/String.h"
 #include "jit/AtomicOperations.h"
 #include "jit/BaselineInspector.h"
 #include "jit/IonBuilder.h"
 #include "jit/JitSpewer.h"
 #include "jit/MIRGraph.h"
 #include "jit/RangeAnalysis.h"
 #include "js/Conversions.h"
 

--- a/js/src/jit/Recover.cpp
+++ b/js/src/jit/Recover.cpp
@@ -3,32 +3,32 @@
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jit/Recover.h"
 
 #include "jsapi.h"
 #include "jsmath.h"
-#include "jsstr.h"
 
 #include "builtin/RegExp.h"
 #include "builtin/SIMD.h"
+#include "builtin/String.h"
 #include "builtin/TypedObject.h"
 #include "gc/Heap.h"
 #include "jit/JitSpewer.h"
 #include "jit/JSJitFrameIter.h"
 #include "jit/MIR.h"
 #include "jit/MIRGraph.h"
 #include "jit/VMFunctions.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/Interpreter-inl.h"
 #include "vm/NativeObject-inl.h"
 
 using namespace js;
 using namespace js::jit;
 
 bool

--- a/js/src/jit/shared/Lowering-shared.cpp
+++ b/js/src/jit/shared/Lowering-shared.cpp
@@ -4,17 +4,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jit/shared/Lowering-shared-inl.h"
 
 #include "jit/LIR.h"
 #include "jit/MIR.h"
 
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 using namespace js;
 using namespace jit;
 
 bool
 LIRGeneratorShared::ShouldReorderCommutative(MDefinition* lhs, MDefinition* rhs, MInstruction* ins)
 {
     // lhs and rhs are used by the commutative operator.

--- a/js/src/jsapi-tests/testErrorInterceptor.cpp
+++ b/js/src/jsapi-tests/testErrorInterceptor.cpp
@@ -1,13 +1,13 @@
 #include "jsapi.h"
 
 #include "jsapi-tests/tests.h"
 
-#include "vm/StringBuffer.h"
+#include "util/StringBuffer.h"
 
 // Tests for JS_GetErrorInterceptorCallback and JS_SetErrorInterceptorCallback.
 
 
 namespace {
 const double EXN_VALUE = 3.14;
 
 static JS::PersistentRootedString gLatestMessage;

--- a/js/src/jsapi-tests/testIndexToString.cpp
+++ b/js/src/jsapi-tests/testIndexToString.cpp
@@ -1,23 +1,23 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsnum.h"
-#include "jsstr.h"
 
+#include "builtin/String.h"
 #include "jsapi-tests/tests.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
 
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using mozilla::ArrayLength;
 
 static const struct TestPair {
     uint32_t num;
     const char* expected;
 } tests[] = {
     { 0, "0" },

--- a/js/src/jsapi-tests/testIntern.cpp
+++ b/js/src/jsapi-tests/testIntern.cpp
@@ -1,17 +1,17 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "gc/FreeOp.h"
 #include "gc/Marking.h"
 #include "jsapi-tests/tests.h"
 #include "vm/JSAtom.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 using mozilla::ArrayLength;
 
 BEGIN_TEST(testAtomizedIsNotPinned)
 {
     /* Try to pick a string that won't be interned by other tests in this runtime. */
     static const char someChars[] = "blah blah blah? blah blah blah";
     JS::Rooted<JSAtom*> atom(cx, js::Atomize(cx, someChars, ArrayLength(someChars)));

--- a/js/src/jsapi-tests/testParseJSON.cpp
+++ b/js/src/jsapi-tests/testParseJSON.cpp
@@ -3,17 +3,17 @@
  */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include <limits>
 #include <string.h>
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "js/Printf.h"
 #include "jsapi-tests/tests.h"
 
 using namespace js;
 
 class AutoInflatedString {
     JSContext * const cx;

--- a/js/src/jsapi-tests/testSavedStacks.cpp
+++ b/js/src/jsapi-tests/testSavedStacks.cpp
@@ -1,16 +1,16 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsfriendapi.h"
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "builtin/TestingFunctions.h"
 #include "jsapi-tests/tests.h"
 #include "vm/ArrayObject.h"
 #include "vm/JSCompartment.h"
 #include "vm/SavedStacks.h"
 
 BEGIN_TEST(testSavedStacks_withNoStack)

--- a/js/src/jsapi-tests/testStringBuffer.cpp
+++ b/js/src/jsapi-tests/testStringBuffer.cpp
@@ -1,18 +1,18 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsapi-tests/tests.h"
+#include "util/StringBuffer.h"
 #include "vm/JSAtom.h"
-#include "vm/StringBuffer.h"
 
 BEGIN_TEST(testStringBuffer_finishString)
 {
     JSString* str = JS_NewStringCopyZ(cx, "foopy");
     CHECK(str);
 
     JS::Rooted<JSAtom*> atom(cx, js::AtomizeString(cx, str));
     CHECK(atom);

--- a/js/src/jsapi-tests/testUTF8.cpp
+++ b/js/src/jsapi-tests/testUTF8.cpp
@@ -3,17 +3,17 @@
  */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/Range.h"
 
 #include "jsapi.h"
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "js/CharacterEncoding.h"
 #include "jsapi-tests/tests.h"
 
 BEGIN_TEST(testUTF8_badUTF8)
 {
     static const char badUTF8[] = "...\xC0...";
     JSString* str = JS_NewStringCopyZ(cx, badUTF8);

--- a/js/src/jsapi-tests/testXDR.cpp
+++ b/js/src/jsapi-tests/testXDR.cpp
@@ -1,16 +1,16 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsfriendapi.h"
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "jsapi-tests/tests.h"
 #include "vm/JSScript.h"
 
 #include "vm/JSScript-inl.h"
 
 static bool
 GetBuildId(JS::BuildIdCharVector* buildId)

--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -25,28 +25,28 @@
 
 #include "jsarray.h"
 #include "jsbool.h"
 #include "jsdate.h"
 #include "jsexn.h"
 #include "jsfriendapi.h"
 #include "jsmath.h"
 #include "jsnum.h"
-#include "jsstr.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
 #include "builtin/AtomicsObject.h"
 #include "builtin/Eval.h"
 #include "builtin/JSON.h"
 #include "builtin/MapObject.h"
 #include "builtin/Promise.h"
 #include "builtin/RegExp.h"
 #include "builtin/Stream.h"
-#include "builtin/SymbolObject.h"
+#include "builtin/String.h"
+#include "builtin/Symbol.h"
 #ifdef ENABLE_SIMD
 # include "builtin/SIMD.h"
 #endif
 #ifdef ENABLE_BINARYDATA
 # include "builtin/TypedObject.h"
 #endif
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/FullParseHandler.h"  // for JS_BufferIsCompileableUnit
@@ -61,16 +61,17 @@
 #include "js/Conversions.h"
 #include "js/Date.h"
 #include "js/Initialization.h"
 #include "js/Proxy.h"
 #include "js/SliceBudget.h"
 #include "js/StructuredClone.h"
 #include "js/Utility.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/AsyncFunction.h"
 #include "vm/AsyncIteration.h"
 #include "vm/DateObject.h"
 #include "vm/Debugger.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/ErrorObject.h"
 #include "vm/HelperThreads.h"
 #include "vm/Interpreter.h"
@@ -80,31 +81,30 @@
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/RegExpStatics.h"
 #include "vm/Runtime.h"
 #include "vm/SavedStacks.h"
 #include "vm/SelfHosting.h"
 #include "vm/Shape.h"
-#include "vm/String.h"
-#include "vm/StringBuffer.h"
-#include "vm/Symbol.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
 #include "vm/WrapperObject.h"
 #include "vm/Xdr.h"
 #include "wasm/AsmJS.h"
 #include "wasm/WasmModule.h"
 
 #include "vm/Interpreter-inl.h"
 #include "vm/JSAtom-inl.h"
 #include "vm/JSFunction-inl.h"
 #include "vm/JSScript-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/SavedStacks-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using mozilla::Maybe;
 using mozilla::PodCopy;
 using mozilla::Some;
 

--- a/js/src/jsarray.cpp
+++ b/js/src/jsarray.cpp
@@ -19,26 +19,26 @@
 #include "jstypes.h"
 #include "jsutil.h"
 
 #include "ds/Sort.h"
 #include "gc/Heap.h"
 #include "jit/InlinableNatives.h"
 #include "js/Class.h"
 #include "js/Conversions.h"
+#include "util/StringBuffer.h"
 #include "vm/ArgumentsObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/SelfHosting.h"
 #include "vm/Shape.h"
-#include "vm/StringBuffer.h"
 #include "vm/TypedArrayObject.h"
 #include "vm/WrapperObject.h"
 
 #include "vm/ArgumentsObject-inl.h"
 #include "vm/ArrayObject-inl.h"
 #include "vm/Caches-inl.h"
 #include "vm/GeckoProfiler-inl.h"
 #include "vm/Interpreter-inl.h"

--- a/js/src/jsbool.cpp
+++ b/js/src/jsbool.cpp
@@ -9,22 +9,22 @@
  */
 
 #include "jsboolinlines.h"
 
 #include "jsapi.h"
 #include "jstypes.h"
 
 #include "jit/InlinableNatives.h"
+#include "util/StringBuffer.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/ProxyObject.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/BooleanObject-inl.h"
 
 using namespace js;
 
 const Class BooleanObject::class_ = {
     "Boolean",
     JSCLASS_HAS_RESERVED_SLOTS(1) | JSCLASS_HAS_CACHED_PROTO(JSProto_Boolean)

--- a/js/src/jsdate.cpp
+++ b/js/src/jsdate.cpp
@@ -23,30 +23,30 @@
 #include "mozilla/Sprintf.h"
 
 #include <ctype.h>
 #include <math.h>
 #include <string.h>
 
 #include "jsapi.h"
 #include "jsnum.h"
-#include "jsstr.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
+#include "builtin/String.h"
 #include "js/Conversions.h"
 #include "js/Date.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/DateTime.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
-#include "vm/String.h"
-#include "vm/StringBuffer.h"
+#include "vm/StringType.h"
 #include "vm/Time.h"
 
 #include "vm/JSObject-inl.h"
 
 using namespace js;
 
 using mozilla::Atomic;
 using mozilla::ArrayLength;

--- a/js/src/jsexn.cpp
+++ b/js/src/jsexn.cpp
@@ -18,25 +18,25 @@
 #include "jsnum.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
 #include "gc/FreeOp.h"
 #include "gc/Marking.h"
 #include "js/CharacterEncoding.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/ErrorObject.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/SavedStacks.h"
 #include "vm/SelfHosting.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/ErrorObject-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/SavedStacks-inl.h"
 
 using namespace js;
 using namespace js::gc;
 

--- a/js/src/jsnum.cpp
+++ b/js/src/jsnum.cpp
@@ -15,31 +15,31 @@
 #include "mozilla/RangedPtr.h"
 
 #ifdef HAVE_LOCALECONV
 #include <locale.h>
 #endif
 #include <math.h>
 #include <string.h>
 
-#include "jsstr.h"
 #include "jstypes.h"
 
+#include "builtin/String.h"
 #include "double-conversion/double-conversion.h"
 #include "js/Conversions.h"
 #include "util/DoubleToString.h"
+#include "util/StringBuffer.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/NativeObject-inl.h"
 #include "vm/NumberObject-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 
 using mozilla::Abs;
 using mozilla::ArrayLength;
 using mozilla::MinNumberValue;
 using mozilla::NegativeInfinity;
 using mozilla::PositiveInfinity;

--- a/js/src/jsnum.h
+++ b/js/src/jsnum.h
@@ -9,17 +9,17 @@
 
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/Range.h"
 
 #include "NamespaceImports.h"
 
 #include "js/Conversions.h"
 
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 
 // This macro is should be `one' if current compiler supports builtin functions
 // like __builtin_sadd_overflow.
 #if __GNUC__ >= 5
     // GCC 5 and above supports these functions.
     #define BUILTIN_CHECKED_ARITHMETIC_SUPPORTED(x) 1
 #else

--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -27,17 +27,17 @@ with Files('gc/**'):
 with Files('jit/**'):
     BUG_COMPONENT = component_jit
 
 # File-specific metadata
 for gcfile in ['devtools/rootAnalysis', 'devtools/gc-ubench', 'devtools/gctrace']:
     with Files(gcfile):
         BUG_COMPONENT = component_gc
 
-for stlfile in ['jsarray.*', 'jsbool*', 'jsdate.*', 'jsnum.*', 'jsstr.*']:
+for stlfile in ['jsarray.*', 'jsbool*', 'jsdate.*', 'jsnum.*']:
     with Files(stlfile):
         BUG_COMPONENT = component_stl
 
 with Files('builtin/intl/*'):
     BUG_COMPONENT = component_intl
 
 
 if CONFIG['JS_BUNDLED_EDITLINE']:
@@ -163,17 +163,18 @@ UNIFIED_SOURCES += [
     'builtin/ModuleObject.cpp',
     'builtin/Object.cpp',
     'builtin/Profilers.cpp',
     'builtin/Promise.cpp',
     'builtin/Reflect.cpp',
     'builtin/ReflectParse.cpp',
     'builtin/SIMD.cpp',
     'builtin/Stream.cpp',
-    'builtin/SymbolObject.cpp',
+    'builtin/String.cpp',
+    'builtin/Symbol.cpp',
     'builtin/TestingFunctions.cpp',
     'builtin/TypedObject.cpp',
     'builtin/WeakMapObject.cpp',
     'builtin/WeakSetObject.cpp',
     'devtools/sharkctl.cpp',
     'ds/Bitmap.cpp',
     'ds/LifoAlloc.cpp',
     'ds/MemoryProtectionExceptionHandler.cpp',
@@ -286,31 +287,32 @@ UNIFIED_SOURCES += [
     'jit/VMFunctions.cpp',
     'jit/WasmBCE.cpp',
     'jsapi.cpp',
     'jsbool.cpp',
     'jsdate.cpp',
     'jsexn.cpp',
     'jsfriendapi.cpp',
     'jsnum.cpp',
-    'jsstr.cpp',
     'perf/jsperf.cpp',
     'proxy/BaseProxyHandler.cpp',
     'proxy/CrossCompartmentWrapper.cpp',
     'proxy/DeadObjectProxy.cpp',
     'proxy/OpaqueCrossCompartmentWrapper.cpp',
     'proxy/Proxy.cpp',
     'proxy/ScriptedProxyHandler.cpp',
     'proxy/SecurityWrapper.cpp',
     'proxy/Wrapper.cpp',
     'threading/Mutex.cpp',
     'threading/ProtectedData.cpp',
     'util/AllocPolicy.cpp',
     'util/NativeStack.cpp',
     'util/Printf.cpp',
+    'util/StringBuffer.cpp',
+    'util/Unicode.cpp',
     'vm/ArgumentsObject.cpp',
     'vm/ArrayBufferObject.cpp',
     'vm/AsyncFunction.cpp',
     'vm/AsyncIteration.cpp',
     'vm/BytecodeUtil.cpp',
     'vm/Caches.cpp',
     'vm/CallNonGenericMethod.cpp',
     'vm/CharacterEncoding.cpp',
@@ -352,29 +354,27 @@ UNIFIED_SOURCES += [
     'vm/SavedStacks.cpp',
     'vm/Scope.cpp',
     'vm/SelfHosting.cpp',
     'vm/Shape.cpp',
     'vm/SharedArrayObject.cpp',
     'vm/SharedImmutableStringsCache.cpp',
     'vm/Stack.cpp',
     'vm/Stopwatch.cpp',
-    'vm/String.cpp',
-    'vm/StringBuffer.cpp',
+    'vm/StringType.cpp',
     'vm/StructuredClone.cpp',
-    'vm/Symbol.cpp',
+    'vm/SymbolType.cpp',
     'vm/TaggedProto.cpp',
     'vm/Time.cpp',
     'vm/TypedArrayObject.cpp',
     'vm/TypeInference.cpp',
     'vm/UbiNode.cpp',
     'vm/UbiNodeCensus.cpp',
     'vm/UbiNodeShortestPaths.cpp',
     'vm/UnboxedObject.cpp',
-    'vm/Unicode.cpp',
     'vm/Value.cpp',
     'vm/Xdr.cpp',
     'wasm/AsmJS.cpp',
     'wasm/WasmBaselineCompile.cpp',
     'wasm/WasmBinaryIterator.cpp',
     'wasm/WasmBinaryToAST.cpp',
     'wasm/WasmBinaryToText.cpp',
     'wasm/WasmBuiltins.cpp',

--- a/js/src/proxy/SecurityWrapper.cpp
+++ b/js/src/proxy/SecurityWrapper.cpp
@@ -4,17 +4,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsapi.h"
 #include "jsfriendapi.h"
 #include "NamespaceImports.h"
 
 #include "js/Wrapper.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 using namespace js;
 
 template <class Base>
 bool
 SecurityWrapper<Base>::enter(JSContext* cx, HandleObject wrapper, HandleId id,
                              Wrapper::Action act, bool mayThrow, bool* bp) const
 {

--- a/js/src/shell/OSObject.cpp
+++ b/js/src/shell/OSObject.cpp
@@ -17,25 +17,25 @@
 #else
 #include <sys/wait.h>
 #include <unistd.h>
 #endif
 
 #include "jsapi.h"
 // For JSFunctionSpecWithHelp
 #include "jsfriendapi.h"
-#include "jsstr.h"
 
+#include "builtin/String.h"
 #include "gc/FreeOp.h"
 #include "js/Conversions.h"
 #include "js/Wrapper.h"
 #include "shell/jsshell.h"
+#include "util/StringBuffer.h"
 #include "util/Windows.h"
 #include "vm/JSObject.h"
-#include "vm/StringBuffer.h"
 #include "vm/TypedArrayObject.h"
 
 #include "vm/JSObject-inl.h"
 
 #ifdef XP_WIN
 # ifndef PATH_MAX
 #  define PATH_MAX (MAX_PATH > _MAX_DIR ? MAX_PATH : _MAX_DIR)
 # endif

--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -85,32 +85,32 @@
 #include "perf/jsperf.h"
 #include "shell/jsoptparse.h"
 #include "shell/jsshell.h"
 #include "shell/OSObject.h"
 #include "threading/ConditionVariable.h"
 #include "threading/ExclusiveData.h"
 #include "threading/LockGuard.h"
 #include "threading/Thread.h"
+#include "util/StringBuffer.h"
 #include "util/Windows.h"
 #include "vm/ArgumentsObject.h"
 #include "vm/Compression.h"
 #include "vm/Debugger.h"
 #include "vm/HelperThreads.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Monitor.h"
 #include "vm/MutexIDs.h"
 #include "vm/Printer.h"
 #include "vm/Shape.h"
 #include "vm/SharedArrayObject.h"
-#include "vm/StringBuffer.h"
 #include "vm/Time.h"
 #include "vm/TypedArrayObject.h"
 #include "vm/WrapperObject.h"
 #include "wasm/WasmJS.h"
 
 #include "vm/ErrorObject-inl.h"
 #include "vm/Interpreter-inl.h"
 #include "vm/JSCompartment-inl.h"

--- a/js/src/shell/jsshell.cpp
+++ b/js/src/shell/jsshell.cpp
@@ -8,17 +8,17 @@
 
 #include "shell/jsshell.h"
 
 #include "mozilla/Sprintf.h"
 
 #include "jsapi.h"
 #include "jsfriendapi.h"
 
-#include "vm/StringBuffer.h"
+#include "util/StringBuffer.h"
 
 using namespace JS;
 
 namespace js {
 namespace shell {
 
 // Generate 'usage' and 'help' properties for the given object.
 // JS_DefineFunctionsWithHelp will define individual function objects with both

rename from js/src/vm/StringBuffer.cpp
rename to js/src/util/StringBuffer.cpp
--- a/js/src/vm/StringBuffer.cpp
+++ b/js/src/util/StringBuffer.cpp
@@ -1,20 +1,20 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "vm/StringBuffer.h"
+#include "util/StringBuffer.h"
 
 #include "mozilla/Range.h"
 
 #include "vm/JSObject-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 
 template <typename CharT, class Buffer>
 static CharT*
 ExtractWellSized(JSContext* cx, Buffer& cb)
 {
     size_t capacity = cb.capacity();

rename from js/src/vm/StringBuffer.h
rename to js/src/util/StringBuffer.h
--- a/js/src/vm/StringBuffer.h
+++ b/js/src/util/StringBuffer.h
@@ -1,16 +1,16 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef vm_StringBuffer_h
-#define vm_StringBuffer_h
+#ifndef util_StringBuffer_h
+#define util_StringBuffer_h
 
 #include "mozilla/DebugOnly.h"
 #include "mozilla/MaybeOneOf.h"
 
 #include "js/Vector.h"
 #include "vm/JSContext.h"
 
 namespace js {
@@ -341,9 +341,9 @@ ValueToStringBuffer(JSContext* cx, const
 inline bool
 BooleanToStringBuffer(bool b, StringBuffer& sb)
 {
     return b ? sb.append("true") : sb.append("false");
 }
 
 }  /* namespace js */
 
-#endif /* vm_StringBuffer_h */
+#endif /* util_StringBuffer_h */

rename from js/src/vm/Unicode.cpp
rename to js/src/util/Unicode.cpp
--- a/js/src/vm/Unicode.cpp
+++ b/js/src/util/Unicode.cpp
@@ -1,16 +1,16 @@
 /* Generated by make_unicode.py DO NOT MODIFY */
 /* Unicode version: 10.0.0 */
 
 /*
  * Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/licenses/publicdomain/
  */
-#include "vm/Unicode.h"
+#include "util/Unicode.h"
 
 using namespace js;
 using namespace js::unicode;
 
 /*
  * So how does indexing work?
  * First let's have a look at a char16_t, 16-bits:
  *              [................]

rename from js/src/vm/Unicode.h
rename to js/src/util/Unicode.h
--- a/js/src/vm/Unicode.h
+++ b/js/src/util/Unicode.h
@@ -1,19 +1,20 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef vm_Unicode_h
-#define vm_Unicode_h
+#ifndef util_Unicode_h
+#define util_Unicode_h
 
 #include "jspubtd.h"
-#include "vm/UnicodeNonBMP.h"
+
+#include "util/UnicodeNonBMP.h"
 
 namespace js {
 namespace unicode {
 
 extern const bool js_isidstart[];
 extern const bool js_isident[];
 extern const bool js_isspace[];
 
@@ -596,9 +597,9 @@ UTF16Decode(char16_t lead, char16_t trai
     MOZ_ASSERT(IsTrailSurrogate(trail));
 
     return (lead << 10) + trail + (NonBMPMin - (LeadSurrogateMin << 10) - TrailSurrogateMin);
 }
 
 } /* namespace unicode */
 } /* namespace js */
 
-#endif /* vm_Unicode_h */
+#endif /* util_Unicode_h */

rename from js/src/vm/UnicodeData.txt
rename to js/src/util/UnicodeData.txt

rename from js/src/vm/UnicodeNonBMP.h
rename to js/src/util/UnicodeNonBMP.h
--- a/js/src/vm/UnicodeNonBMP.h
+++ b/js/src/util/UnicodeNonBMP.h
@@ -2,18 +2,18 @@
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /* Generated by make_unicode.py DO NOT MODIFY */
 /* Unicode version: 10.0.0 */
 
-#ifndef vm_UnicodeNonBMP_h
-#define vm_UnicodeNonBMP_h
+#ifndef util_UnicodeNonBMP_h
+#define util_UnicodeNonBMP_h
 
 // |macro| receives the following arguments
 //   macro(FROM, TO, LEAD, TRAIL_FROM, TRAIL_TO, DIFF)
 //     FROM:       code point where the range starts
 //     TO:         code point where the range ends
 //     LEAD:       common lead surrogate of FROM and TO
 //     TRAIL_FROM: trail surrogate of FROM
 //     TRAIL_FROM: trail surrogate of TO
@@ -63,9 +63,9 @@
 // U+1E922 ADLAM SMALL LETTER ALIF .. U+1E943 ADLAM SMALL LETTER SHA
 #define FOR_EACH_NON_BMP_REV_CASE_FOLDING(macro) \
     macro(0x10428, 0x1044f, 0xd801, 0xdc28, 0xdc4f, -40) \
     macro(0x104d8, 0x104fb, 0xd801, 0xdcd8, 0xdcfb, -40) \
     macro(0x10cc0, 0x10cf2, 0xd803, 0xdcc0, 0xdcf2, -64) \
     macro(0x118c0, 0x118df, 0xd806, 0xdcc0, 0xdcdf, -32) \
     macro(0x1e922, 0x1e943, 0xd83a, 0xdd22, 0xdd43, -34)
 
-#endif /* vm_UnicodeNonBMP_h */
+#endif /* util_UnicodeNonBMP_h */

rename from js/src/vm/make_unicode.py
rename to js/src/util/make_unicode.py

--- a/js/src/vm/ArrayObject-inl.h
+++ b/js/src/vm/ArrayObject-inl.h
@@ -5,17 +5,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef vm_ArrayObject_inl_h
 #define vm_ArrayObject_inl_h
 
 #include "vm/ArrayObject.h"
 
 #include "gc/GCTrace.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/TypeInference-inl.h"
 
 namespace js {
 
 inline void
 ArrayObject::setLength(JSContext* cx, uint32_t length)

--- a/js/src/vm/BytecodeUtil.cpp
+++ b/js/src/vm/BytecodeUtil.cpp
@@ -20,37 +20,37 @@
 #include <algorithm>
 #include <ctype.h>
 #include <inttypes.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "jsapi.h"
 #include "jsnum.h"
-#include "jsstr.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
+#include "builtin/String.h"
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/SourceNotes.h"
 #include "gc/FreeOp.h"
 #include "gc/GCInternals.h"
 #include "js/CharacterEncoding.h"
 #include "js/Printf.h"
+#include "util/StringBuffer.h"
 #include "vm/CodeCoverage.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/JSAtom.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Opcodes.h"
 #include "vm/Shape.h"
-#include "vm/StringBuffer.h"
 
 #include "gc/PrivateIterators-inl.h"
 #include "vm/JSCompartment-inl.h"
 #include "vm/JSContext-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/JSScript-inl.h"
 
 using namespace js;

--- a/js/src/vm/ErrorObject.cpp
+++ b/js/src/vm/ErrorObject.cpp
@@ -9,17 +9,17 @@
 
 #include "mozilla/Range.h"
 
 #include "jsexn.h"
 
 #include "js/CallArgs.h"
 #include "js/CharacterEncoding.h"
 #include "vm/GlobalObject.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/SavedStacks-inl.h"
 #include "vm/Shape-inl.h"
 
 using namespace js;
 

--- a/js/src/vm/GeckoProfiler.cpp
+++ b/js/src/vm/GeckoProfiler.cpp
@@ -11,18 +11,18 @@
 #include "jsnum.h"
 
 #include "gc/PublicIterators.h"
 #include "jit/BaselineFrame.h"
 #include "jit/BaselineJIT.h"
 #include "jit/JitcodeMap.h"
 #include "jit/JitFrames.h"
 #include "jit/JSJitFrameIter.h"
+#include "util/StringBuffer.h"
 #include "vm/JSScript.h"
-#include "vm/StringBuffer.h"
 
 #include "gc/Marking-inl.h"
 
 using namespace js;
 
 using mozilla::DebugOnly;
 
 GeckoProfilerThread::GeckoProfilerThread()

--- a/js/src/vm/GlobalObject.cpp
+++ b/js/src/vm/GlobalObject.cpp
@@ -17,17 +17,17 @@
 #include "builtin/JSON.h"
 #include "builtin/MapObject.h"
 #include "builtin/ModuleObject.h"
 #include "builtin/Object.h"
 #include "builtin/Promise.h"
 #include "builtin/RegExp.h"
 #include "builtin/SelfHostingDefines.h"
 #include "builtin/Stream.h"
-#include "builtin/SymbolObject.h"
+#include "builtin/Symbol.h"
 #include "builtin/TypedObject.h"
 #include "builtin/WeakMapObject.h"
 #include "builtin/WeakSetObject.h"
 #include "gc/FreeOp.h"
 #include "js/ProtoKey.h"
 #include "vm/Debugger.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/HelperThreads.h"

--- a/js/src/vm/Interpreter-inl.h
+++ b/js/src/vm/Interpreter-inl.h
@@ -5,27 +5,27 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef vm_Interpreter_inl_h
 #define vm_Interpreter_inl_h
 
 #include "vm/Interpreter.h"
 
 #include "jsnum.h"
-#include "jsstr.h"
 
+#include "builtin/String.h"
 #include "jit/Ion.h"
 #include "vm/ArgumentsObject.h"
 #include "vm/JSCompartment.h"
 
 #include "vm/EnvironmentObject-inl.h"
 #include "vm/JSAtom-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/Stack-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 #include "vm/UnboxedObject-inl.h"
 
 namespace js {
 
 /*
  * Every possible consumer of MagicValue(JS_OPTIMIZED_ARGUMENTS) (as determined
  * by ScriptAnalysis::needsArgsObj) must check for these magic values and, when
  * one is received, act as if the value were the function's ArgumentsObject.

--- a/js/src/vm/Interpreter.cpp
+++ b/js/src/vm/Interpreter.cpp
@@ -15,40 +15,40 @@
 #include "mozilla/Maybe.h"
 #include "mozilla/Sprintf.h"
 
 #include <string.h>
 
 #include "jsarray.h"
 #include "jslibmath.h"
 #include "jsnum.h"
-#include "jsstr.h"
 
 #include "builtin/Eval.h"
+#include "builtin/String.h"
 #include "jit/AtomicOperations.h"
 #include "jit/BaselineJIT.h"
 #include "jit/Ion.h"
 #include "jit/IonAnalysis.h"
 #include "jit/Jit.h"
+#include "util/StringBuffer.h"
 #include "vm/AsyncFunction.h"
 #include "vm/AsyncIteration.h"
 #include "vm/BytecodeUtil.h"
 #include "vm/Debugger.h"
 #include "vm/GeneratorObject.h"
 #include "vm/Iteration.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Opcodes.h"
 #include "vm/Scope.h"
 #include "vm/Shape.h"
 #include "vm/Stopwatch.h"
-#include "vm/StringBuffer.h"
 #include "vm/TraceLogging.h"
 
 #include "jsboolinlines.h"
 
 #include "jit/JitFrames-inl.h"
 #include "vm/Debugger-inl.h"
 #include "vm/EnvironmentObject-inl.h"
 #include "vm/GeckoProfiler-inl.h"

--- a/js/src/vm/Iteration.cpp
+++ b/js/src/vm/Iteration.cpp
@@ -32,17 +32,17 @@
 #include "vm/JSScript.h"
 #include "vm/Shape.h"
 #include "vm/TypedArrayObject.h"
 
 #include "vm/JSScript-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/ReceiverGuard-inl.h"
 #include "vm/Stack-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using mozilla::DebugOnly;
 using mozilla::Maybe;
 using mozilla::PodCopy;
 using mozilla::PodEqual;

--- a/js/src/vm/JSAtom-inl.h
+++ b/js/src/vm/JSAtom-inl.h
@@ -9,17 +9,17 @@
 
 #include "vm/JSAtom.h"
 
 #include "mozilla/RangedPtr.h"
 
 #include "jsnum.h"
 
 #include "vm/Runtime.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 
 inline jsid
 AtomToId(JSAtom* atom)
 {
     JS_STATIC_ASSERT(JSID_INT_MIN == 0);
 

--- a/js/src/vm/JSAtom.cpp
+++ b/js/src/vm/JSAtom.cpp
@@ -12,29 +12,29 @@
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/EndianUtils.h"
 #include "mozilla/RangedPtr.h"
 #include "mozilla/Unused.h"
 
 #include <string.h>
 
-#include "jsstr.h"
 #include "jstypes.h"
 
+#include "builtin/String.h"
 #include "gc/Marking.h"
 #include "vm/JSContext.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 #include "vm/Xdr.h"
 
 #include "gc/AtomMarking-inl.h"
 #include "vm/JSCompartment-inl.h"
 #include "vm/JSContext-inl.h"
 #include "vm/JSObject-inl.h"
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 using namespace js;
 using namespace js::gc;
 
 using mozilla::ArrayEnd;
 using mozilla::ArrayLength;
 using mozilla::Maybe;
 using mozilla::Nothing;

--- a/js/src/vm/JSContext-inl.h
+++ b/js/src/vm/JSContext-inl.h
@@ -11,17 +11,17 @@
 
 #include "builtin/Object.h"
 #include "jit/JitFrames.h"
 #include "proxy/Proxy.h"
 #include "vm/HelperThreads.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSCompartment.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
 namespace js {
 
 class CompartmentChecker
 {
     JSCompartment* compartment;
 
   public:

--- a/js/src/vm/JSContext.cpp
+++ b/js/src/vm/JSContext.cpp
@@ -25,19 +25,19 @@
 # include <string>
 #endif // ANDROID
 #ifdef XP_WIN
 # include <processthreadsapi.h>
 #endif // XP_WIN
 
 #include "jsexn.h"
 #include "jspubtd.h"
-#include "jsstr.h"
 #include "jstypes.h"
 
+#include "builtin/String.h"
 #include "gc/FreeOp.h"
 #include "gc/Marking.h"
 #include "jit/Ion.h"
 #include "jit/PcScriptCache.h"
 #include "js/CharacterEncoding.h"
 #include "js/Printf.h"
 #include "util/DoubleToString.h"
 #include "util/NativeStack.h"

--- a/js/src/vm/JSFunction.cpp
+++ b/js/src/vm/JSFunction.cpp
@@ -14,44 +14,44 @@
 #include "mozilla/CheckedInt.h"
 #include "mozilla/Maybe.h"
 #include "mozilla/Range.h"
 
 #include <string.h>
 
 #include "jsapi.h"
 #include "jsarray.h"
-#include "jsstr.h"
 #include "jstypes.h"
 
 #include "builtin/Eval.h"
 #include "builtin/Object.h"
 #include "builtin/SelfHostingDefines.h"
+#include "builtin/String.h"
 #include "frontend/BytecodeCompiler.h"
 #include "frontend/TokenStream.h"
 #include "gc/Marking.h"
 #include "gc/Policy.h"
 #include "jit/InlinableNatives.h"
 #include "jit/Ion.h"
 #include "js/CallNonGenericMethod.h"
 #include "js/Proxy.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/AsyncFunction.h"
 #include "vm/AsyncIteration.h"
 #include "vm/Debugger.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/SelfHosting.h"
 #include "vm/Shape.h"
 #include "vm/SharedImmutableStringsCache.h"
-#include "vm/StringBuffer.h"
 #include "vm/WrapperObject.h"
 #include "vm/Xdr.h"
 #include "wasm/AsmJS.h"
 
 #include "vm/Interpreter-inl.h"
 #include "vm/JSScript-inl.h"
 #include "vm/Stack-inl.h"
 

--- a/js/src/vm/JSONParser.cpp
+++ b/js/src/vm/JSONParser.cpp
@@ -10,18 +10,18 @@
 #include "mozilla/RangedPtr.h"
 #include "mozilla/Sprintf.h"
 
 #include <ctype.h>
 
 #include "jsarray.h"
 #include "jsnum.h"
 
+#include "util/StringBuffer.h"
 #include "vm/JSCompartment.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/NativeObject-inl.h"
 
 using namespace js;
 
 using mozilla::RangedPtr;
 
 JSONParserBase::~JSONParserBase()

--- a/js/src/vm/JSONParser.h
+++ b/js/src/vm/JSONParser.h
@@ -8,17 +8,17 @@
 #define vm_JSONParser_h
 
 #include "mozilla/Attributes.h"
 #include "mozilla/Range.h"
 
 #include "jspubtd.h"
 
 #include "ds/IdValuePair.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 
 // JSONParser base class. JSONParser is templatized to work on either Latin1
 // or TwoByte input strings, JSONParserBase holds all state and methods that
 // can be shared between the two encodings.
 class MOZ_STACK_CLASS JSONParserBase
 {

--- a/js/src/vm/JSObject.cpp
+++ b/js/src/vm/JSObject.cpp
@@ -17,23 +17,23 @@
 
 #include <string.h>
 
 #include "jsapi.h"
 #include "jsarray.h"
 #include "jsexn.h"
 #include "jsfriendapi.h"
 #include "jsnum.h"
-#include "jsstr.h"
 #include "jstypes.h"
 #include "jsutil.h"
 
 #include "builtin/Eval.h"
 #include "builtin/Object.h"
-#include "builtin/SymbolObject.h"
+#include "builtin/String.h"
+#include "builtin/Symbol.h"
 #include "frontend/BytecodeCompiler.h"
 #include "gc/Policy.h"
 #include "jit/BaselineJIT.h"
 #include "js/MemoryMetrics.h"
 #include "js/Proxy.h"
 #include "js/UbiNode.h"
 #include "js/UniquePtr.h"
 #include "js/Wrapper.h"

--- a/js/src/vm/JSObject.h
+++ b/js/src/vm/JSObject.h
@@ -10,17 +10,17 @@
 #include "mozilla/MemoryReporting.h"
 
 #include "gc/Barrier.h"
 #include "js/Conversions.h"
 #include "js/GCVector.h"
 #include "js/HeapAPI.h"
 #include "vm/Printer.h"
 #include "vm/Shape.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 #include "vm/Xdr.h"
 
 namespace JS {
 struct ClassInfo;
 } // namespace JS
 
 namespace js {
 

--- a/js/src/vm/JSScript.cpp
+++ b/js/src/vm/JSScript.cpp
@@ -31,29 +31,29 @@
 #include "gc/FreeOp.h"
 #include "jit/BaselineJIT.h"
 #include "jit/Ion.h"
 #include "jit/IonCode.h"
 #include "js/MemoryMetrics.h"
 #include "js/Printf.h"
 #include "js/Utility.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/ArgumentsObject.h"
 #include "vm/BytecodeUtil.h"
 #include "vm/Compression.h"
 #include "vm/Debugger.h"
 #include "vm/JSAtom.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/JSObject.h"
 #include "vm/Opcodes.h"
 #include "vm/SelfHosting.h"
 #include "vm/Shape.h"
 #include "vm/SharedImmutableStringsCache.h"
-#include "vm/StringBuffer.h"
 #include "vm/Xdr.h"
 #include "vtune/VTuneWrapper.h"
 
 #include "gc/Marking-inl.h"
 #include "vm/EnvironmentObject-inl.h"
 #include "vm/JSFunction-inl.h"
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"

--- a/js/src/vm/MemoryMetrics.cpp
+++ b/js/src/vm/MemoryMetrics.cpp
@@ -13,18 +13,18 @@
 #include "jit/BaselineJIT.h"
 #include "jit/Ion.h"
 #include "vm/ArrayObject.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Runtime.h"
 #include "vm/Shape.h"
-#include "vm/String.h"
-#include "vm/Symbol.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
 #include "vm/WrapperObject.h"
 #include "wasm/WasmInstance.h"
 #include "wasm/WasmJS.h"
 #include "wasm/WasmModule.h"
 
 using mozilla::MallocSizeOf;
 using mozilla::Move;
 using mozilla::PodCopy;

--- a/js/src/vm/NativeObject.h
+++ b/js/src/vm/NativeObject.h
@@ -17,17 +17,17 @@
 
 #include "gc/Barrier.h"
 #include "gc/Heap.h"
 #include "gc/Marking.h"
 #include "js/Value.h"
 #include "vm/JSObject.h"
 #include "vm/Shape.h"
 #include "vm/ShapedObject.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 #include "vm/TypeInference.h"
 
 namespace js {
 
 class Shape;
 class TenuringTracer;
 
 /*

--- a/js/src/vm/RegExpObject.cpp
+++ b/js/src/vm/RegExpObject.cpp
@@ -4,34 +4,34 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "vm/RegExpObject.h"
 
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PodOperations.h"
 
-#include "jsstr.h"
+#include "builtin/String.h"
 #ifdef DEBUG
 #include "jsutil.h"
 #endif
 
 #include "builtin/RegExp.h"
 #include "frontend/TokenStream.h"
 #include "gc/HashUtil.h"
 #ifdef DEBUG
 #include "irregexp/RegExpBytecode.h"
 #endif
 #include "irregexp/RegExpParser.h"
+#include "util/StringBuffer.h"
 #include "vm/MatchPairs.h"
 #include "vm/RegExpStatics.h"
-#include "vm/StringBuffer.h"
 #include "vm/TraceLogging.h"
 #ifdef DEBUG
-#include "vm/Unicode.h"
+#include "util/Unicode.h"
 #endif
 #include "vm/Xdr.h"
 
 #include "vm/JSObject-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/Shape-inl.h"
 
 using namespace js;

--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -44,17 +44,17 @@
 #include "vm/DateTime.h"
 #include "vm/GeckoProfiler.h"
 #include "vm/JSAtom.h"
 #include "vm/JSScript.h"
 #include "vm/Scope.h"
 #include "vm/SharedImmutableStringsCache.h"
 #include "vm/Stack.h"
 #include "vm/Stopwatch.h"
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 #include "wasm/WasmSignalHandlers.h"
 
 #ifdef _MSC_VER
 #pragma warning(push)
 #pragma warning(disable:4100) /* Silence unreferenced formal parameter warnings */
 #endif
 
 namespace js {

--- a/js/src/vm/SavedStacks.cpp
+++ b/js/src/vm/SavedStacks.cpp
@@ -21,22 +21,22 @@
 
 #include "gc/FreeOp.h"
 #include "gc/HashUtil.h"
 #include "gc/Marking.h"
 #include "gc/Policy.h"
 #include "gc/Rooting.h"
 #include "js/CharacterEncoding.h"
 #include "js/Vector.h"
+#include "util/StringBuffer.h"
 #include "vm/Debugger.h"
 #include "vm/GeckoProfiler.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSScript.h"
 #include "vm/SavedFrame.h"
-#include "vm/StringBuffer.h"
 #include "vm/Time.h"
 #include "vm/WrapperObject.h"
 
 #include "vm/GeckoProfiler-inl.h"
 #include "vm/JSContext-inl.h"
 #include "vm/NativeObject-inl.h"
 #include "vm/Stack-inl.h"
 

--- a/js/src/vm/Scope.cpp
+++ b/js/src/vm/Scope.cpp
@@ -4,19 +4,19 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "vm/Scope.h"
 
 #include "builtin/ModuleObject.h"
 #include "gc/Allocator.h"
 #include "gc/FreeOp.h"
+#include "util/StringBuffer.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/JSScript.h"
-#include "vm/StringBuffer.h"
 #include "wasm/WasmInstance.h"
 
 #include "gc/ObjectKind-inl.h"
 #include "vm/Shape-inl.h"
 
 using namespace js;
 
 using mozilla::Maybe;

--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -9,17 +9,16 @@
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Casting.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Maybe.h"
 
 #include "jsarray.h"
 #include "jsdate.h"
 #include "jsfriendapi.h"
-#include "jsstr.h"
 #include "selfhosted.out.h"
 
 #include "builtin/intl/Collator.h"
 #include "builtin/intl/DateTimeFormat.h"
 #include "builtin/intl/IntlObject.h"
 #include "builtin/intl/NumberFormat.h"
 #include "builtin/intl/PluralRules.h"
 #include "builtin/intl/RelativeTimeFormat.h"
@@ -27,38 +26,39 @@
 #include "builtin/ModuleObject.h"
 #include "builtin/Object.h"
 #include "builtin/Promise.h"
 #include "builtin/Reflect.h"
 #include "builtin/RegExp.h"
 #include "builtin/SelfHostingDefines.h"
 #include "builtin/SIMD.h"
 #include "builtin/Stream.h"
+#include "builtin/String.h"
 #include "builtin/TypedObject.h"
 #include "builtin/WeakMapObject.h"
 #include "gc/HashUtil.h"
 #include "gc/Marking.h"
 #include "gc/Policy.h"
 #include "jit/AtomicOperations.h"
 #include "jit/InlinableNatives.h"
 #include "js/CharacterEncoding.h"
 #include "js/Date.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/ArgumentsObject.h"
 #include "vm/Compression.h"
 #include "vm/GeneratorObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Iteration.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
 #include "vm/JSFunction.h"
 #include "vm/Printer.h"
 #include "vm/RegExpObject.h"
-#include "vm/String.h"
-#include "vm/StringBuffer.h"
+#include "vm/StringType.h"
 #include "vm/TypedArrayObject.h"
 #include "vm/WrapperObject.h"
 
 #include "gc/PrivateIterators-inl.h"
 #include "vm/BooleanObject-inl.h"
 #include "vm/JSAtom-inl.h"
 #include "vm/JSFunction-inl.h"
 #include "vm/JSObject-inl.h"

--- a/js/src/vm/Shape.h
+++ b/js/src/vm/Shape.h
@@ -25,18 +25,18 @@
 #include "gc/Rooting.h"
 #include "js/HashTable.h"
 #include "js/MemoryMetrics.h"
 #include "js/RootingAPI.h"
 #include "js/UbiNode.h"
 #include "vm/JSAtom.h"
 #include "vm/ObjectGroup.h"
 #include "vm/Printer.h"
-#include "vm/String.h"
-#include "vm/Symbol.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
 
 #ifdef _MSC_VER
 #pragma warning(push)
 #pragma warning(disable:4800)
 #pragma warning(push)
 #pragma warning(disable:4100) /* Silence unreferenced formal parameter warnings */
 #endif
 

--- a/js/src/vm/SharedImmutableStringsCache.cpp
+++ b/js/src/vm/SharedImmutableStringsCache.cpp
@@ -1,17 +1,17 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "vm/SharedImmutableStringsCache-inl.h"
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 namespace js {
 
 SharedImmutableString::SharedImmutableString(
     ExclusiveData<SharedImmutableStringsCache::Inner>::Guard& locked,
     SharedImmutableStringsCache::StringBox* box)
   : cache_(locked)
   , box_(box)

--- a/js/src/vm/SharedImmutableStringsCache.h
+++ b/js/src/vm/SharedImmutableStringsCache.h
@@ -8,17 +8,17 @@
 #define vm_SharedImmutableStringsCache_h
 
 #include "mozilla/Maybe.h"
 #include "mozilla/UniquePtr.h"
 
 #include <cstring>
 #include <new> // for placement new
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "js/HashTable.h"
 #include "js/Utility.h"
 
 #include "threading/ExclusiveData.h"
 
 #include "vm/MutexIDs.h"
 

--- a/js/src/vm/StringObject.h
+++ b/js/src/vm/StringObject.h
@@ -2,17 +2,17 @@
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef vm_StringObject_h
 #define vm_StringObject_h
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "vm/JSObject.h"
 #include "vm/Shape.h"
 
 namespace js {
 
 class StringObject : public NativeObject
 {

rename from js/src/vm/String-inl.h
rename to js/src/vm/StringType-inl.h
--- a/js/src/vm/String-inl.h
+++ b/js/src/vm/StringType-inl.h
@@ -1,18 +1,18 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef vm_String_inl_h
-#define vm_String_inl_h
+#ifndef vm_StringType_inl_h
+#define vm_StringType_inl_h
 
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 #include "mozilla/PodOperations.h"
 #include "mozilla/Range.h"
 
 #include "gc/Allocator.h"
 #include "gc/FreeOp.h"
 #include "gc/Marking.h"
 #include "vm/JSCompartment.h"
@@ -423,9 +423,9 @@ JSExternalString::finalize(js::FreeOp* f
         fop->free_(nonInlineCharsRaw());
         return;
     }
 
     const JSStringFinalizer* fin = externalFinalizer();
     fin->finalize(fin, const_cast<char16_t*>(rawTwoByteChars()));
 }
 
-#endif /* vm_String_inl_h */
+#endif /* vm_StringType_inl_h */

rename from js/src/vm/String.cpp
rename to js/src/vm/StringType.cpp
--- a/js/src/vm/String.cpp
+++ b/js/src/vm/StringType.cpp
@@ -1,15 +1,15 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "vm/String-inl.h"
+#include "vm/StringType-inl.h"
 
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PodOperations.h"
 #include "mozilla/RangedPtr.h"
 #include "mozilla/TypeTraits.h"
 #include "mozilla/Unused.h"
 

rename from js/src/vm/String.h
rename to js/src/vm/StringType.h
--- a/js/src/vm/String.h
+++ b/js/src/vm/StringType.h
@@ -1,25 +1,25 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef vm_String_h
-#define vm_String_h
+#ifndef vm_StringType_h
+#define vm_StringType_h
 
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PodOperations.h"
 #include "mozilla/Range.h"
 
 #include "jsapi.h"
 #include "jsfriendapi.h"
-#include "jsstr.h"
 
+#include "builtin/String.h"
 #include "gc/Barrier.h"
 #include "gc/Cell.h"
 #include "gc/Heap.h"
 #include "gc/Nursery.h"
 #include "gc/Rooting.h"
 #include "js/CharacterEncoding.h"
 #include "js/RootingAPI.h"
 
@@ -1706,9 +1706,9 @@ template<>
 inline JSString*
 TenuredCell::as<JSString>() {
     MOZ_ASSERT(is<JSString>());
     return reinterpret_cast<JSString*>(this);
 }
 }
 }
 
-#endif /* vm_String_h */
+#endif /* vm_StringType_h */

rename from js/src/vm/Symbol.cpp
rename to js/src/vm/SymbolType.cpp
--- a/js/src/vm/Symbol.cpp
+++ b/js/src/vm/SymbolType.cpp
@@ -1,22 +1,22 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "vm/Symbol.h"
+#include "vm/SymbolType.h"
 
-#include "builtin/SymbolObject.h"
+#include "builtin/Symbol.h"
 #include "gc/Allocator.h"
 #include "gc/Rooting.h"
+#include "util/StringBuffer.h"
 #include "vm/JSCompartment.h"
 #include "vm/JSContext.h"
-#include "vm/StringBuffer.h"
 
 #include "vm/JSCompartment-inl.h"
 
 using JS::Symbol;
 using namespace js;
 
 Symbol*
 Symbol::newInternal(JSContext* cx, JS::SymbolCode code, uint32_t hash, JSAtom* description,

rename from js/src/vm/Symbol.h
rename to js/src/vm/SymbolType.h
--- a/js/src/vm/Symbol.h
+++ b/js/src/vm/SymbolType.h
@@ -1,32 +1,32 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef vm_Symbol_h
-#define vm_Symbol_h
+#ifndef vm_SymbolType_h
+#define vm_SymbolType_h
 
 #include "mozilla/Attributes.h"
 
 #include <stdio.h>
 
 #include "jsapi.h"
 
 #include "gc/Barrier.h"
 #include "gc/Tracer.h"
 #include "js/AllocPolicy.h"
 #include "js/GCHashTable.h"
 #include "js/RootingAPI.h"
 #include "js/TypeDecls.h"
 #include "js/Utility.h"
 #include "vm/Printer.h"
-#include "vm/String.h"
+#include "vm/StringType.h"
 
 namespace js {
 class AutoLockForExclusiveAccess;
 } // namespace js
 
 namespace JS {
 
 class Symbol : public js::gc::TenuredCell
@@ -142,9 +142,9 @@ class SymbolRegistry : public GCHashSet<
 };
 
 // ES6 rev 27 (2014 Aug 24) 19.4.3.3
 bool
 SymbolDescriptiveString(JSContext* cx, JS::Symbol* sym, JS::MutableHandleValue result);
 
 } /* namespace js */
 
-#endif /* vm_Symbol_h */
+#endif /* vm_SymbolType_h */

--- a/js/src/vm/TraceLoggingGraph.cpp
+++ b/js/src/vm/TraceLoggingGraph.cpp
@@ -12,17 +12,17 @@
 #else
 #include <unistd.h>
 #endif
 
 #include "mozilla/EndianUtils.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/ScopeExit.h"
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "js/UniquePtr.h"
 #include "threading/LockGuard.h"
 #include "threading/Thread.h"
 #include "vm/TraceLogging.h"
 
 #ifndef DEFAULT_TRACE_LOG_DIR
 # if defined(_WIN32)

--- a/js/src/vm/TraceLoggingTypes.h
+++ b/js/src/vm/TraceLoggingTypes.h
@@ -2,17 +2,17 @@
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef TraceLoggingTypes_h
 #define TraceLoggingTypes_h
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "js/AllocPolicy.h"
 
 // Tree items, meaning they have a start and stop and form a nested tree.
 #define TRACELOGGER_TREE_ITEMS(_)                     \
     _(AnnotateScripts)                                \
     _(Baseline)                                       \
     _(BaselineCompilation)                            \

--- a/js/src/vm/TypeInference-inl.h
+++ b/js/src/vm/TypeInference-inl.h
@@ -10,17 +10,17 @@
 #define vm_TypeInference_inl_h
 
 #include "vm/TypeInference.h"
 
 #include "mozilla/BinarySearch.h"
 #include "mozilla/Casting.h"
 #include "mozilla/PodOperations.h"
 
-#include "builtin/SymbolObject.h"
+#include "builtin/Symbol.h"
 #include "gc/GC.h"
 #include "jit/BaselineJIT.h"
 #include "vm/ArrayObject.h"
 #include "vm/BooleanObject.h"
 #include "vm/NumberObject.h"
 #include "vm/SharedArrayObject.h"
 #include "vm/StringObject.h"
 #include "vm/TypedArrayObject.h"

--- a/js/src/vm/TypeInference.cpp
+++ b/js/src/vm/TypeInference.cpp
@@ -8,17 +8,17 @@
 
 #include "mozilla/DebugOnly.h"
 #include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PodOperations.h"
 #include "mozilla/Sprintf.h"
 
 #include "jsapi.h"
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "gc/HashUtil.h"
 #include "jit/BaselineJIT.h"
 #include "jit/CompileInfo.h"
 #include "jit/Ion.h"
 #include "jit/IonAnalysis.h"
 #include "jit/JitCompartment.h"
 #include "jit/OptimizationTracking.h"

--- a/js/src/vm/UbiNode.cpp
+++ b/js/src/vm/UbiNode.cpp
@@ -8,34 +8,34 @@
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Range.h"
 #include "mozilla/Scoped.h"
 
 #include <algorithm>
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 #include "jit/IonCode.h"
 #include "js/Debug.h"
 #include "js/TracingAPI.h"
 #include "js/TypeDecls.h"
 #include "js/Utility.h"
 #include "js/Vector.h"
 #include "vm/Debugger.h"
 #include "vm/EnvironmentObject.h"
 #include "vm/GlobalObject.h"
 #include "vm/JSContext.h"
 #include "vm/JSObject.h"
 #include "vm/JSScript.h"
 #include "vm/Scope.h"
 #include "vm/Shape.h"
-#include "vm/String.h"
-#include "vm/Symbol.h"
+#include "vm/StringType.h"
+#include "vm/SymbolType.h"
 
 #include "vm/Debugger-inl.h"
 #include "vm/JSObject-inl.h"
 
 using namespace js;
 
 using mozilla::RangedPtr;
 using JS::DispatchTyped;

--- a/js/src/vm/UbiNodeShortestPaths.cpp
+++ b/js/src/vm/UbiNodeShortestPaths.cpp
@@ -4,17 +4,17 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "js/UbiNodeShortestPaths.h"
 
 #include "mozilla/Maybe.h"
 #include "mozilla/Move.h"
 
-#include "jsstr.h"
+#include "builtin/String.h"
 
 namespace JS {
 namespace ubi {
 
 JS_PUBLIC_API(BackEdge::Ptr)
 BackEdge::clone() const
 {
     BackEdge::Ptr clone(js_new<BackEdge>());

--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -19,29 +19,29 @@
 #include "wasm/AsmJS.h"
 
 #include "mozilla/Attributes.h"
 #include "mozilla/Compression.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/Unused.h"
 
 #include "jsmath.h"
-#include "jsstr.h"
 #include "jsutil.h"
 
 #include "builtin/SIMD.h"
+#include "builtin/String.h"
 #include "frontend/Parser.h"
 #include "gc/Policy.h"
 #include "jit/AtomicOperations.h"
 #include "js/MemoryMetrics.h"
 #include "js/Printf.h"
 #include "js/Wrapper.h"
+#include "util/StringBuffer.h"
 #include "vm/ErrorReporting.h"
 #include "vm/SelfHosting.h"
-#include "vm/StringBuffer.h"
 #include "vm/Time.h"
 #include "vm/TypedArrayObject.h"
 #include "wasm/WasmCompile.h"
 #include "wasm/WasmGenerator.h"
 #include "wasm/WasmInstance.h"
 #include "wasm/WasmIonCompile.h"
 #include "wasm/WasmJS.h"
 #include "wasm/WasmSerialize.h"

--- a/js/src/wasm/WasmBinaryToText.cpp
+++ b/js/src/wasm/WasmBinaryToText.cpp
@@ -15,18 +15,18 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 #include "wasm/WasmBinaryToText.h"
 
 #include "jsnum.h"
 
+#include "util/StringBuffer.h"
 #include "vm/ArrayBufferObject.h"
-#include "vm/StringBuffer.h"
 #include "wasm/WasmAST.h"
 #include "wasm/WasmBinaryToAST.h"
 #include "wasm/WasmDebug.h"
 #include "wasm/WasmTextUtils.h"
 #include "wasm/WasmTypes.h"
 
 using namespace js;
 using namespace js::wasm;

--- a/js/src/wasm/WasmDebug.cpp
+++ b/js/src/wasm/WasmDebug.cpp
@@ -19,18 +19,18 @@
 #include "wasm/WasmDebug.h"
 
 #include "mozilla/BinarySearch.h"
 
 #include "ds/Sort.h"
 #include "gc/FreeOp.h"
 #include "jit/ExecutableAllocator.h"
 #include "jit/MacroAssembler.h"
+#include "util/StringBuffer.h"
 #include "vm/Debugger.h"
-#include "vm/StringBuffer.h"
 #include "wasm/WasmBinaryToText.h"
 #include "wasm/WasmInstance.h"
 #include "wasm/WasmValidate.h"
 
 using namespace js;
 using namespace js::jit;
 using namespace js::wasm;
 

--- a/js/src/wasm/WasmJS.cpp
+++ b/js/src/wasm/WasmJS.cpp
@@ -23,19 +23,19 @@
 #include "mozilla/Maybe.h"
 #include "mozilla/RangedPtr.h"
 
 #include "builtin/Promise.h"
 #include "gc/FreeOp.h"
 #include "jit/AtomicOperations.h"
 #include "jit/JitOptions.h"
 #include "js/Printf.h"
+#include "util/StringBuffer.h"
 #include "vm/Interpreter.h"
-#include "vm/String.h"
-#include "vm/StringBuffer.h"
+#include "vm/StringType.h"
 #include "wasm/WasmBaselineCompile.h"
 #include "wasm/WasmCompile.h"
 #include "wasm/WasmInstance.h"
 #include "wasm/WasmIonCompile.h"
 #include "wasm/WasmModule.h"
 #include "wasm/WasmSignalHandlers.h"
 #include "wasm/WasmStubs.h"
 #include "wasm/WasmValidate.h"

--- a/js/src/wasm/WasmTextToBinary.cpp
+++ b/js/src/wasm/WasmTextToBinary.cpp
@@ -18,18 +18,18 @@
 
 #include "wasm/WasmTextToBinary.h"
 
 #include "mozilla/CheckedInt.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/Maybe.h"
 
 #include "jsnum.h"
-#include "jsstr.h"
-
+
+#include "builtin/String.h"
 #include "ds/LifoAlloc.h"
 #include "js/CharacterEncoding.h"
 #include "js/HashTable.h"
 #include "js/Printf.h"
 #include "util/DoubleToString.h"
 #include "wasm/WasmAST.h"
 #include "wasm/WasmTypes.h"
 #include "wasm/WasmValidate.h"

--- a/js/src/wasm/WasmTextUtils.cpp
+++ b/js/src/wasm/WasmTextUtils.cpp
@@ -13,17 +13,17 @@
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 #include "wasm/WasmTextUtils.h"
 
-#include "vm/StringBuffer.h"
+#include "util/StringBuffer.h"
 #include "wasm/WasmTypes.h"
 
 using namespace js;
 using namespace jit;
 using namespace wasm;
 
 using mozilla::IsNaN;
 

--- a/js/src/wasm/WasmTextUtils.h
+++ b/js/src/wasm/WasmTextUtils.h
@@ -16,17 +16,17 @@
  * limitations under the License.
  */
 
 #ifndef wasm_text_utils
 #define wasm_text_utils
 
 #include "NamespaceImports.h"
 
-#include "vm/StringBuffer.h"
+#include "util/StringBuffer.h"
 
 namespace js {
 namespace wasm {
 
 template<size_t base>
 MOZ_MUST_USE bool
 RenderInBase(StringBuffer& sb, uint64_t num);