--- a/js/ipc/ObjectWrapperParent.cpp
+++ b/js/ipc/ObjectWrapperParent.cpp
@@ -383,17 +383,17 @@ jsval_to_nsString(JSContext* cx, jsid fr
         *to = chars;
         return true;
     }
     return false;
 }
 
 /*static*/ JSBool
 ObjectWrapperParent::CPOW_AddProperty(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                                      JSMutableHandleValue vp)
+                                      MutableHandleValue vp)
 {
     CPOW_LOG(("Calling CPOW_AddProperty (%s)...",
               JSVAL_TO_CSTR(cx, id)));
 
     ObjectWrapperParent* self = Unwrap(cx, obj);
     if (!self)
         return with_error(cx, JS_FALSE, "Unwrapping failed in CPOW_AddProperty");
 
@@ -410,17 +410,17 @@ ObjectWrapperParent::CPOW_AddProperty(JS
     return (self->Manager()->RequestRunToCompletion() &&
             self->CallAddProperty(in_id,
                                   aco.StatusPtr()) &&
             aco.Ok());
 }
 
 /*static*/ JSBool
 ObjectWrapperParent::CPOW_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                                      JSMutableHandleValue vp)
+                                      MutableHandleValue vp)
 {
     CPOW_LOG(("Calling CPOW_GetProperty (%s)...",
               JSVAL_TO_CSTR(cx, id)));
 
     ObjectWrapperParent* self = Unwrap(cx, obj);
     if (!self)
         return with_error(cx, JS_FALSE, "Unwrapping failed in CPOW_GetProperty");
 
@@ -437,17 +437,17 @@ ObjectWrapperParent::CPOW_GetProperty(JS
             self->CallGetProperty(in_id,
                                   aco.StatusPtr(), &out_v) &&
             aco.Ok() &&
             self->jsval_from_JSVariant(cx, out_v, vp.address()));
 }
 
 /*static*/ JSBool
 ObjectWrapperParent::CPOW_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, 
-                                      JSBool strict, JSMutableHandleValue vp)
+                                      JSBool strict, MutableHandleValue vp)
 {
     CPOW_LOG(("Calling CPOW_SetProperty (%s)...",
               JSVAL_TO_CSTR(cx, id)));
 
     ObjectWrapperParent* self = Unwrap(cx, obj);
     if (!self)
         return with_error(cx, JS_FALSE, "Unwrapping failed in CPOW_SetProperty");
 
@@ -609,17 +609,17 @@ ObjectWrapperParent::CPOW_NewResolve(JSC
         JS_DefinePropertyById(cx, obj2, id, JSVAL_VOID, NULL, NULL,
                               JSPROP_ENUMERATE);
     }
     return JS_TRUE;
 }
 
 /*static*/ JSBool
 ObjectWrapperParent::CPOW_Convert(JSContext *cx, JSHandleObject obj, JSType type,
-                                  JSMutableHandleValue vp)
+                                  MutableHandleValue vp)
 {
     CPOW_LOG(("Calling CPOW_Convert (to %s)...",
               JS_GetTypeName(cx, type)));
 
     ObjectWrapperParent* self = Unwrap(cx, obj);
     if (!self)
         return with_error(cx, JS_FALSE, "Unwrapping failed in CPOW_Convert");
 
@@ -703,17 +703,17 @@ ObjectWrapperParent::CPOW_Construct(JSCo
 
     return (constructor->Manager()->RequestRunToCompletion() &&
             constructor->CallConstruct(in_argv, aco.StatusPtr(), &out_powp) &&
             aco.Ok() &&
             jsval_from_PObjectWrapperParent(cx, out_powp, vp));
 }
 
 /*static*/ JSBool
-ObjectWrapperParent::CPOW_HasInstance(JSContext *cx, JSHandleObject obj, JSMutableHandleValue v,
+ObjectWrapperParent::CPOW_HasInstance(JSContext *cx, JSHandleObject obj, MutableHandleValue v,
                                       JSBool *bp)
 {
     CPOW_LOG(("Calling CPOW_HasInstance..."));
 
     *bp = JS_FALSE;
 
     ObjectWrapperParent* self = Unwrap(cx, obj);
     if (!self)

--- a/js/ipc/ObjectWrapperParent.h
+++ b/js/ipc/ObjectWrapperParent.h
@@ -54,52 +54,52 @@ protected:
 
     ContextWrapperParent* Manager();
 
 private:
 
     mutable JSObject* mObj;
 
     static JSBool
-    CPOW_AddProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp);
+    CPOW_AddProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JS::MutableHandleValue vp);
 
     static JSBool
     CPOW_DelProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool *succeeded);
 
     static JSBool
-    CPOW_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp);
+    CPOW_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JS::MutableHandleValue vp);
     
     static JSBool
-    CPOW_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JSMutableHandleValue vp);
+    CPOW_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JS::MutableHandleValue vp);
 
     JSBool NewEnumerateInit(JSContext* cx, jsval* statep, jsid* idp);
     JSBool NewEnumerateNext(JSContext* cx, jsval* statep, jsid* idp);
     JSBool NewEnumerateDestroy(JSContext* cx, jsval state);
     static JSBool
     CPOW_NewEnumerate(JSContext *cx, JSHandleObject obj, JSIterateOp enum_op,
                       jsval *statep, jsid *idp);
 
     static JSBool
     CPOW_NewResolve(JSContext *cx, JSHandleObject obj, JSHandleId id, unsigned flags,
                     JS::MutableHandleObject objp);
 
     static JSBool
-    CPOW_Convert(JSContext *cx, JSHandleObject obj, JSType type, JSMutableHandleValue vp);
+    CPOW_Convert(JSContext *cx, JSHandleObject obj, JSType type, JS::MutableHandleValue vp);
 
     static void
     CPOW_Finalize(js::FreeOp* fop, JSObject* obj);
 
     static JSBool
     CPOW_Call(JSContext* cx, unsigned argc, jsval* vp);
 
     static JSBool
     CPOW_Construct(JSContext *cx, unsigned argc, jsval *vp);
 
     static JSBool
-    CPOW_HasInstance(JSContext *cx, JSHandleObject obj, JSMutableHandleValue vp, JSBool *bp);
+    CPOW_HasInstance(JSContext *cx, JSHandleObject obj, JS::MutableHandleValue vp, JSBool *bp);
 
     static bool jsval_to_JSVariant(JSContext* cx, jsval from, JSVariant* to);
     static bool jsval_from_JSVariant(JSContext* cx, const JSVariant& from,
                                      jsval* to);
     static bool boolean_from_JSVariant(JSContext* cx, const JSVariant& from,
                                        JSBool* to);
     static bool
     JSObject_to_PObjectWrapperParent(JSContext* cx, JSObject* from, PObjectWrapperParent** to);

--- a/js/xpconnect/shell/xpcshell.cpp
+++ b/js/xpconnect/shell/xpcshell.cpp
@@ -79,16 +79,17 @@
 #include <unistd.h>     /* for isatty() */
 #endif
 
 #ifdef MOZ_CRASHREPORTER
 #include "nsICrashReporter.h"
 #endif
 
 using namespace mozilla;
+using namespace JS;
 
 class XPCShellDirProvider : public nsIDirectoryServiceProvider2
 {
 public:
     NS_DECL_ISUPPORTS_INHERITED
     NS_DECL_NSIDIRECTORYSERVICEPROVIDER
     NS_DECL_NSIDIRECTORYSERVICEPROVIDER2
 
@@ -140,17 +141,17 @@ int gExitCode = 0;
 JSBool gQuitting = false;
 static JSBool reportWarnings = true;
 static JSBool compileOnly = false;
 
 JSPrincipals *gJSPrincipals = nullptr;
 nsAutoString *gWorkingDirectory = nullptr;
 
 static JSBool
-GetLocationProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp)
+GetLocationProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, MutableHandleValue vp)
 {
 #if !defined(XP_WIN) && !defined(XP_UNIX)
     //XXX: your platform should really implement this
     return false;
 #else
     JSScript *script;
     JS_DescribeScriptedCaller(cx, &script, NULL);
     const char *filename = JS_GetScriptFilename(cx, script);
@@ -846,17 +847,17 @@ static const JSFunctionSpec glob_functio
 
 JSClass global_class = {
     "global", 0,
     JS_PropertyStub,  JS_DeletePropertyStub,  JS_PropertyStub,  JS_StrictPropertyStub,
     JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,   nullptr
 };
 
 static JSBool
-env_setProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JSMutableHandleValue vp)
+env_setProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, MutableHandleValue vp)
 {
 /* XXX porting may be easy, but these don't seem to supply setenv by default */
 #if !defined XP_OS2 && !defined SOLARIS
     JSString *valstr;
     JS::Rooted<JSString*> idstr(cx);
     int rv;
 
     jsval idval;

--- a/js/xpconnect/src/XPCComponents.cpp
+++ b/js/xpconnect/src/XPCComponents.cpp
@@ -2955,17 +2955,17 @@ sandbox_finalize(JSFreeOp *fop, JSObject
         static_cast<nsIScriptObjectPrincipal *>(xpc_GetJSPrivate(obj));
     MOZ_ASSERT(sop);
     static_cast<SandboxPrivate *>(sop)->ForgetGlobalObject();
     NS_IF_RELEASE(sop);
     DestroyProtoAndIfaceCache(obj);
 }
 
 static JSBool
-sandbox_convert(JSContext *cx, JSHandleObject obj, JSType type, JSMutableHandleValue vp)
+sandbox_convert(JSContext *cx, JSHandleObject obj, JSType type, MutableHandleValue vp)
 {
     if (type == JSTYPE_OBJECT) {
         vp.set(OBJECT_TO_JSVAL(obj));
         return true;
     }
 
     return JS_ConvertStub(cx, obj, type, vp);
 }
@@ -3121,19 +3121,19 @@ bool BindPropertyOp(JSContext *cx, Op &o
     if (!func)
         return false;
     op = JS_DATA_TO_FUNC_PTR(Op, func.get());
     desc->attrs |= attrFlag;
     return true;
 }
 
 extern JSBool
-XPC_WN_Helper_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp);
+XPC_WN_Helper_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, MutableHandleValue vp);
 extern JSBool
-XPC_WN_Helper_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JSMutableHandleValue vp);
+XPC_WN_Helper_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, MutableHandleValue vp);
 
 bool
 xpc::SandboxProxyHandler::getPropertyDescriptor(JSContext *cx,
                                                 JS::Handle<JSObject*> proxy,
                                                 JS::Handle<jsid> id,
                                                 PropertyDescriptor *desc,
                                                 unsigned flags)
 {
@@ -4823,17 +4823,17 @@ nsXPCComponents::SetProperty(nsIXPConnec
         return NS_ERROR_FAILURE;
     }
 
     return NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN;
 }
 
 static JSBool
 ContentComponentsGetterOp(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                          JSMutableHandleValue vp)
+                          MutableHandleValue vp)
 {
     // If chrome is accessing the Components object of content, allow.
     MOZ_ASSERT(nsContentUtils::GetCurrentJSContext() == cx);
     if (nsContentUtils::IsCallerChrome())
         return true;
 
     // If the caller is XBL, this is ok.
     if (nsContentUtils::IsCallerXBL())

--- a/js/xpconnect/src/XPCLocale.cpp
+++ b/js/xpconnect/src/XPCLocale.cpp
@@ -17,16 +17,18 @@
 #include "nsIPlatformCharset.h"
 #include "nsILocaleService.h"
 #include "nsICollation.h"
 #include "nsIServiceManager.h"
 #include "nsUnicharUtils.h"
 
 #include "xpcpublic.h"
 
+using namespace JS;
+
 /**
  * JS locale callbacks implemented by XPCOM modules.  These are theoretically
  * safe for use on multiple threads.  Unfortunately, the intl code underlying
  * these XPCOM modules doesn't yet support this, so in practice
  * XPCLocaleCallbacks are limited to the main thread.
  */
 struct XPCLocaleCallbacks : public JSLocaleCallbacks
 {
@@ -67,42 +69,42 @@ struct XPCLocaleCallbacks : public JSLoc
     MOZ_ASSERT(lc->localeToUnicode == LocaleToUnicode);
 
     XPCLocaleCallbacks* ths = static_cast<XPCLocaleCallbacks*>(lc);
     ths->AssertThreadSafety();
     return ths;
   }
 
   static JSBool
-  LocaleToUpperCase(JSContext *cx, JSHandleString src, JSMutableHandleValue rval)
+  LocaleToUpperCase(JSContext *cx, JSHandleString src, MutableHandleValue rval)
   {
     return ChangeCase(cx, src, rval, ToUpperCase);
   }
 
   static JSBool
-  LocaleToLowerCase(JSContext *cx, JSHandleString src, JSMutableHandleValue rval)
+  LocaleToLowerCase(JSContext *cx, JSHandleString src, MutableHandleValue rval)
   {
     return ChangeCase(cx, src, rval, ToLowerCase);
   }
 
   static JSBool
-  LocaleToUnicode(JSContext* cx, const char* src, JSMutableHandleValue rval)
+  LocaleToUnicode(JSContext* cx, const char* src, MutableHandleValue rval)
   {
     return This(JS_GetRuntime(cx))->ToUnicode(cx, src, rval);
   }
 
   static JSBool
-  LocaleCompare(JSContext *cx, JSHandleString src1, JSHandleString src2, JSMutableHandleValue rval)
+  LocaleCompare(JSContext *cx, JSHandleString src1, JSHandleString src2, MutableHandleValue rval)
   {
     return This(JS_GetRuntime(cx))->Compare(cx, src1, src2, rval);
   }
 
 private:
   static JSBool
-  ChangeCase(JSContext* cx, JSHandleString src, JSMutableHandleValue rval,
+  ChangeCase(JSContext* cx, JSHandleString src, MutableHandleValue rval,
              void(*changeCaseFnc)(const nsAString&, nsAString&))
   {
     nsDependentJSString depStr;
     if (!depStr.init(cx, src)) {
       return false;
     }
 
     nsAutoString result;
@@ -114,17 +116,17 @@ private:
       return false;
     }
 
     rval.set(STRING_TO_JSVAL(ucstr));
     return true;
   }
 
   JSBool
-  Compare(JSContext *cx, JSHandleString src1, JSHandleString src2, JSMutableHandleValue rval)
+  Compare(JSContext *cx, JSHandleString src1, JSHandleString src2, MutableHandleValue rval)
   {
     nsresult rv;
 
     if (!mCollation) {
       nsCOMPtr<nsILocaleService> localeService =
         do_GetService(NS_LOCALESERVICE_CONTRACTID, &rv);
 
       if (NS_SUCCEEDED(rv)) {
@@ -161,17 +163,17 @@ private:
       return false;
     }
 
     rval.set(INT_TO_JSVAL(result));
     return true;
   }
 
   JSBool
-  ToUnicode(JSContext* cx, const char* src, JSMutableHandleValue rval)
+  ToUnicode(JSContext* cx, const char* src, MutableHandleValue rval)
   {
     nsresult rv;
 
     if (!mDecoder) {
       // use app default locale
       nsCOMPtr<nsILocaleService> localeService =
         do_GetService(NS_LOCALESERVICE_CONTRACTID, &rv);
       if (NS_SUCCEEDED(rv)) {

--- a/js/xpconnect/src/XPCQuickStubs.cpp
+++ b/js/xpconnect/src/XPCQuickStubs.cpp
@@ -390,17 +390,17 @@ void
 xpc_qsThrowBadSetterValue(JSContext *cx, nsresult rv, JSObject *obj,
                           uint16_t name_index)
 {
     xpc_qsThrowBadSetterValue(cx, rv, obj, xpc_qsStringTable + name_index);
 }
 
 JSBool
 xpc_qsGetterOnlyPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                             JSMutableHandleValue vp)
+                             MutableHandleValue vp)
 {
     return JS_ReportErrorFlagsAndNumber(cx,
                                         JSREPORT_WARNING | JSREPORT_STRICT |
                                         JSREPORT_STRICT_MODE_ERROR,
                                         js_GetErrorMessage, NULL,
                                         JSMSG_GETTER_ONLY);
 }
 

--- a/js/xpconnect/src/XPCQuickStubs.h
+++ b/js/xpconnect/src/XPCQuickStubs.h
@@ -126,17 +126,17 @@ void
 xpc_qsThrowBadSetterValue(JSContext *cx, nsresult rv, JSObject *obj,
                           const char* propName);
 void
 xpc_qsThrowBadSetterValue(JSContext *cx, nsresult rv, JSObject *obj,
                           uint16_t name_index);
 
 
 JSBool
-xpc_qsGetterOnlyPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JSMutableHandleValue vp);
+xpc_qsGetterOnlyPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict, JS::MutableHandleValue vp);
 
 JSBool
 xpc_qsGetterOnlyNativeStub(JSContext *cx, unsigned argc, jsval *vp);
 
 /* Functions for converting values between COM and JS. */
 
 inline JSBool
 xpc_qsInt64ToJsval(JSContext *cx, int64_t i, jsval *rv)
@@ -564,29 +564,29 @@ xpc_qsSameResult(int32_t result1, int32_
 
 #define XPC_QS_ASSERT_CONTEXT_OK(cx) xpc_qsAssertContextOK(cx)
 #else
 #define XPC_QS_ASSERT_CONTEXT_OK(cx) ((void) 0)
 #endif
 
 // Apply |op| to |obj|, |id|, and |vp|. If |op| is a setter, treat the assignment as lenient.
 template<typename Op>
-inline JSBool ApplyPropertyOp(JSContext *cx, Op op, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp);
+inline JSBool ApplyPropertyOp(JSContext *cx, Op op, JSHandleObject obj, JSHandleId id, JS::MutableHandleValue vp);
 
 template<>
 inline JSBool
-ApplyPropertyOp<JSPropertyOp>(JSContext *cx, JSPropertyOp op, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp)
+ApplyPropertyOp<JSPropertyOp>(JSContext *cx, JSPropertyOp op, JSHandleObject obj, JSHandleId id, JS::MutableHandleValue vp)
 {
     return op(cx, obj, id, vp);
 }
 
 template<>
 inline JSBool
 ApplyPropertyOp<JSStrictPropertyOp>(JSContext *cx, JSStrictPropertyOp op, JSHandleObject obj,
-                                    JSHandleId id, JSMutableHandleValue vp)
+                                    JSHandleId id, JS::MutableHandleValue vp)
 {
     return op(cx, obj, id, true, vp);
 }
 
 template<typename Op>
 JSBool
 PropertyOpForwarder(JSContext *cx, unsigned argc, jsval *vp)
 {

--- a/js/xpconnect/src/XPCWrappedNativeJSOps.cpp
+++ b/js/xpconnect/src/XPCWrappedNativeJSOps.cpp
@@ -425,59 +425,59 @@ DefinePropertyIfFound(XPCCallContext& cc
     return JS_DefinePropertyById(ccx, obj, id, JSVAL_VOID, getter, setter,
                                  propFlags);
 }
 
 /***************************************************************************/
 /***************************************************************************/
 
 static JSBool
-XPC_WN_OnlyIWrite_AddPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp)
+XPC_WN_OnlyIWrite_AddPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, MutableHandleValue vp)
 {
     XPCCallContext ccx(JS_CALLER, cx, obj, NullPtr(), id);
     XPCWrappedNative* wrapper = ccx.GetWrapper();
     THROW_AND_RETURN_IF_BAD_WRAPPER(cx, wrapper);
 
     // Allow only XPConnect to add/set the property
     if (ccx.GetResolveName() == id)
         return true;
 
     return Throw(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN, cx);
 }
 
 static JSBool
 XPC_WN_OnlyIWrite_SetPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                                  JSMutableHandleValue vp)
+                                  MutableHandleValue vp)
 {
     return XPC_WN_OnlyIWrite_AddPropertyStub(cx, obj, id, vp);
 }
 
 static JSBool
 XPC_WN_CannotModifyPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                                JSMutableHandleValue vp)
+                                MutableHandleValue vp)
 {
     return Throw(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN, cx);
 }
 
 static JSBool
 XPC_WN_CantDeletePropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id,
                               JSBool *succeeded)
 {
     return Throw(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN, cx);
 }
 
 static JSBool
 XPC_WN_CannotModifyStrictPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                                      JSMutableHandleValue vp)
+                                      MutableHandleValue vp)
 {
     return XPC_WN_CannotModifyPropertyStub(cx, obj, id, vp);
 }
 
 static JSBool
-XPC_WN_Shared_Convert(JSContext *cx, JSHandleObject obj, JSType type, JSMutableHandleValue vp)
+XPC_WN_Shared_Convert(JSContext *cx, JSHandleObject obj, JSType type, MutableHandleValue vp)
 {
     if (type == JSTYPE_OBJECT) {
         vp.set(OBJECT_TO_JSVAL(obj));
         return true;
     }
 
     XPCCallContext ccx(JS_CALLER, cx, obj);
     XPCWrappedNative* wrapper = ccx.GetWrapper();
@@ -751,30 +751,30 @@ XPCWrappedNativeJSClass XPC_WN_NoHelper_
   },
   0 // interfacesBitmap
 };
 
 
 /***************************************************************************/
 
 static JSBool
-XPC_WN_MaybeResolvingPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSMutableHandleValue vp)
+XPC_WN_MaybeResolvingPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, MutableHandleValue vp)
 {
     XPCCallContext ccx(JS_CALLER, cx, obj);
     XPCWrappedNative* wrapper = ccx.GetWrapper();
     THROW_AND_RETURN_IF_BAD_WRAPPER(cx, wrapper);
 
     if (ccx.GetResolvingWrapper() == wrapper)
         return true;
     return Throw(NS_ERROR_XPC_CANT_MODIFY_PROP_ON_WN, cx);
 }
 
 static JSBool
 XPC_WN_MaybeResolvingStrictPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                                        JSMutableHandleValue vp)
+                                        MutableHandleValue vp)
 {
     return XPC_WN_MaybeResolvingPropertyStub(cx, obj, id, vp);
 }
 
 static JSBool
 XPC_WN_MaybeResolvingDeletePropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool *succeeded)
 {
     XPCCallContext ccx(JS_CALLER, cx, obj);
@@ -805,17 +805,17 @@ XPC_WN_MaybeResolvingDeletePropertyStub(
 
 #define POST_HELPER_STUB                                                      \
     if (NS_FAILED(rv))                                                        \
         return Throw(rv, cx);                                                 \
     return retval;
 
 static JSBool
 XPC_WN_Helper_AddProperty(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                          JSMutableHandleValue vp)
+                          MutableHandleValue vp)
 {
     PRE_HELPER_STUB
     AddProperty(wrapper, cx, obj, id, vp.address(), &retval);
     POST_HELPER_STUB
 }
 
 static JSBool
 XPC_WN_Helper_DelProperty(JSContext *cx, JSHandleObject obj, JSHandleId id,
@@ -823,43 +823,43 @@ XPC_WN_Helper_DelProperty(JSContext *cx,
 {
     PRE_HELPER_STUB
     DelProperty(wrapper, cx, obj, id, &retval);
     POST_HELPER_STUB
 }
 
 JSBool
 XPC_WN_Helper_GetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                          JSMutableHandleValue vp)
+                          MutableHandleValue vp)
 {
     PRE_HELPER_STUB
     GetProperty(wrapper, cx, obj, id, vp.address(), &retval);
     POST_HELPER_STUB
 }
 
 JSBool
 XPC_WN_Helper_SetProperty(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                          JSMutableHandleValue vp)
+                          MutableHandleValue vp)
 {
     PRE_HELPER_STUB
     SetProperty(wrapper, cx, obj, id, vp.address(), &retval);
     POST_HELPER_STUB
 }
 
 static JSBool
-XPC_WN_Helper_Convert(JSContext *cx, JSHandleObject obj, JSType type, JSMutableHandleValue vp)
+XPC_WN_Helper_Convert(JSContext *cx, JSHandleObject obj, JSType type, MutableHandleValue vp)
 {
     PRE_HELPER_STUB
     Convert(wrapper, cx, obj, type, vp.address(), &retval);
     POST_HELPER_STUB
 }
 
 static JSBool
 XPC_WN_Helper_CheckAccess(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                          JSAccessMode mode, JSMutableHandleValue vp)
+                          JSAccessMode mode, MutableHandleValue vp)
 {
     PRE_HELPER_STUB
     CheckAccess(wrapper, cx, obj, id, mode, vp.address(), &retval);
     POST_HELPER_STUB
 }
 
 static JSBool
 XPC_WN_Helper_Call(JSContext *cx, unsigned argc, jsval *vp)
@@ -896,17 +896,17 @@ XPC_WN_Helper_Construct(JSContext *cx, u
     MOZ_ASSERT(obj == ccx.GetFlattenedJSObject());
 
     PRE_HELPER_STUB
     Construct(wrapper, cx, obj, args, &retval);
     POST_HELPER_STUB
 }
 
 static JSBool
-XPC_WN_Helper_HasInstance(JSContext *cx, JSHandleObject obj, JSMutableHandleValue valp, JSBool *bp)
+XPC_WN_Helper_HasInstance(JSContext *cx, JSHandleObject obj, MutableHandleValue valp, JSBool *bp)
 {
     bool retval2;
     PRE_HELPER_STUB
     HasInstance(wrapper, cx, obj, valp, &retval2, &retval);
     *bp = retval2;
     POST_HELPER_STUB
 }
 
@@ -1030,17 +1030,17 @@ XPC_WN_Helper_NewResolve(JSContext *cx, 
         if ( DONT_ENUM_STATICS )
             use enumerate stub - don't use this JSOp thing at all
         else
             do shared enumerate - don't use this JSOp thing at all
 */
 
 JSBool
 XPC_WN_JSOp_Enumerate(JSContext *cx, JSHandleObject obj, JSIterateOp enum_op,
-                      JSMutableHandleValue statep, MutableHandleId idp)
+                      MutableHandleValue statep, MutableHandleId idp)
 {
     js::Class *clazz = js::GetObjectClass(obj);
     if (!IS_WN_CLASS(clazz) || clazz == &XPC_WN_NoHelper_JSClass.base) {
         // obj must be a prototype object or a wrapper w/o a
         // helper. Short circuit this call to the default
         // implementation.
 
         return JS_EnumerateState(cx, obj, enum_op, statep, idp);
@@ -1525,17 +1525,17 @@ js::Class XPC_WN_ModsAllowed_NoCall_Prot
     JS_NULL_CLASS_EXT,
     XPC_WN_NoCall_ObjectOps
 };
 
 /***************************************************************************/
 
 static JSBool
 XPC_WN_OnlyIWrite_Proto_AddPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id,
-                                        JSMutableHandleValue vp)
+                                        MutableHandleValue vp)
 {
     NS_ASSERTION(js::GetObjectClass(obj) == &XPC_WN_NoMods_WithCall_Proto_JSClass ||
                  js::GetObjectClass(obj) == &XPC_WN_NoMods_NoCall_Proto_JSClass,
                  "bad proto");
 
     XPCWrappedNativeProto* self =
         (XPCWrappedNativeProto*) xpc_GetJSPrivate(obj);
     if (!self)
@@ -1549,17 +1549,17 @@ XPC_WN_OnlyIWrite_Proto_AddPropertyStub(
     if (ccx.GetResolveName() == id)
         return true;
 
     return Throw(NS_ERROR_XPC_BAD_OP_ON_WN_PROTO, cx);
 }
 
 static JSBool
 XPC_WN_OnlyIWrite_Proto_SetPropertyStub(JSContext *cx, JSHandleObject obj, JSHandleId id, JSBool strict,
-                                        JSMutableHandleValue vp)
+                                        MutableHandleValue vp)
 {
     return XPC_WN_OnlyIWrite_Proto_AddPropertyStub(cx, obj, id, vp);
 }
 
 static JSBool
 XPC_WN_NoMods_Proto_Resolve(JSContext *cx, JSHandleObject obj, JSHandleId id)
 {
     NS_ASSERTION(js::GetObjectClass(obj) == &XPC_WN_NoMods_WithCall_Proto_JSClass ||

--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -1197,17 +1197,17 @@ extern js::Class XPC_WN_NoHelper_Proto_J
 extern JSBool
 XPC_WN_CallMethod(JSContext *cx, unsigned argc, jsval *vp);
 
 extern JSBool
 XPC_WN_GetterSetter(JSContext *cx, unsigned argc, jsval *vp);
 
 extern JSBool
 XPC_WN_JSOp_Enumerate(JSContext *cx, JSHandleObject obj, JSIterateOp enum_op,
-                      JSMutableHandleValue statep, JS::MutableHandleId idp);
+                      JS::MutableHandleValue statep, JS::MutableHandleId idp);
 
 extern JSObject*
 XPC_WN_JSOp_ThisObject(JSContext *cx, JSHandleObject obj);
 
 // Macros to initialize Object or Function like XPC_WN classes
 #define XPC_WN_WithCall_ObjectOps                                             \
     {                                                                         \
         nullptr, /* lookupGeneric */                                          \

--- a/js/xpconnect/wrappers/XrayWrapper.h
+++ b/js/xpconnect/wrappers/XrayWrapper.h
@@ -17,19 +17,19 @@
 // we pull them out of the Wrapper inheritance hierarchy and create a
 // little world around them.
 
 class XPCWrappedNative;
 
 namespace xpc {
 
 JSBool
-holder_get(JSContext *cx, JSHandleObject holder, JSHandleId id, JSMutableHandleValue vp);
+holder_get(JSContext *cx, JSHandleObject holder, JSHandleId id, JS::MutableHandleValue vp);
 JSBool
-holder_set(JSContext *cx, JSHandleObject holder, JSHandleId id, JSBool strict, JSMutableHandleValue vp);
+holder_set(JSContext *cx, JSHandleObject holder, JSHandleId id, JSBool strict, JS::MutableHandleValue vp);
 
 namespace XrayUtils {
 
 extern JSClass HolderClass;
 
 bool CloneExpandoChain(JSContext *cx, JSObject *src, JSObject *dst);
 
 bool