--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -3590,19 +3590,17 @@ void
 BytecodeEmitter::reportError(ParseNode* pn, unsigned errorNumber, ...)
 {
     MOZ_ASSERT_IF(!pn, this->scriptStartOffsetSet);
     uint32_t offset = pn ? pn->pn_pos.begin : this->scriptStartOffset;
 
     va_list args;
     va_start(args, errorNumber);
 
-    ErrorMetadata metadata;
-    if (parser.computeErrorMetadata(&metadata, offset))
-        ReportCompileError(cx, Move(metadata), nullptr, JSREPORT_ERROR, errorNumber, args);
+    parser.errorAtVA(offset, errorNumber, &args);
 
     va_end(args);
 }
 
 bool
 BytecodeEmitter::reportExtraWarning(ParseNode* pn, unsigned errorNumber, ...)
 {
     MOZ_ASSERT_IF(!pn, this->scriptStartOffsetSet);

--- a/js/src/frontend/EitherParser.h
+++ b/js/src/frontend/EitherParser.h
@@ -88,24 +88,16 @@ struct GetTokenStream
 template<class Parser>
 struct ParserOptions
 {
     static constexpr auto get() -> decltype(&Parser::options) {
         return &Parser::options;
     }
 };
 
-template<class TokenStream>
-struct TokenStreamComputeErrorMetadata
-{
-    static constexpr auto get() -> decltype(&TokenStream::computeErrorMetadata) {
-        return &TokenStream::computeErrorMetadata;
-    }
-};
-
 template<class Parser>
 struct ParserNewObjectBox
 {
     static constexpr auto get() -> decltype(&Parser::newObjectBox) {
         return &Parser::newObjectBox;
     }
 };
 
@@ -129,16 +121,24 @@ template<class Handler>
 struct HandlerIsSuperBase
 {
     static constexpr auto get() -> decltype(&Handler::isSuperBase) {
         return &Handler::isSuperBase;
     }
 };
 
 template<class TokenStream>
+struct TokenStreamErrorAtVA
+{
+    static constexpr auto get() -> decltype(&TokenStream::errorAtVA) {
+        return &TokenStream::errorAtVA;
+    }
+};
+
+template<class TokenStream>
 struct TokenStreamReportExtraWarning
 {
     static constexpr auto get() -> decltype(&TokenStream::reportExtraWarningErrorNumberVA) {
         return &TokenStream::reportExtraWarningErrorNumberVA;
     }
 };
 
 // Generic matchers.
@@ -200,23 +200,16 @@ class EitherParser
         return parser.match(detail::ScriptSourceMatcher());
     }
 
     const JS::ReadOnlyCompileOptions& options() {
         InvokeMemberFunction<detail::GetParser, detail::ParserOptions> optionsMatcher;
         return parser.match(mozilla::Move(optionsMatcher));
     }
 
-    MOZ_MUST_USE bool computeErrorMetadata(ErrorMetadata* metadata, uint32_t offset) {
-        InvokeMemberFunction<detail::GetTokenStream, detail::TokenStreamComputeErrorMetadata,
-                             ErrorMetadata*, uint32_t>
-            matcher { metadata, offset };
-        return parser.match(mozilla::Move(matcher));
-    }
-
     ObjectBox* newObjectBox(JSObject* obj) {
         InvokeMemberFunction<detail::GetParser, detail::ParserNewObjectBox,
                              JSObject*>
             matcher { obj };
         return parser.match(mozilla::Move(matcher));
     }
 
     Node singleBindingFromDeclaration(Node decl) {
@@ -241,19 +234,27 @@ class EitherParser
     }
 
     template<typename... Args>
     MOZ_MUST_USE bool warningNoOffset(Args&&... args) {
         return parser.match(detail::ParserBaseMatcher()).warningNoOffset(mozilla::Forward<Args>(args)...);
     }
 
     template<typename... Args>
+    void errorAtVA(Args&&... args) {
+        InvokeMemberFunction<detail::GetTokenStream, detail::TokenStreamErrorAtVA, Args...>
+            matcher { mozilla::Forward<Args>(args)... };
+        return parser.match(mozilla::Move(matcher));
+    }
+
+    template<typename... Args>
     MOZ_MUST_USE bool reportExtraWarningErrorNumberVA(Args&&... args) {
         InvokeMemberFunction<detail::GetTokenStream, detail::TokenStreamReportExtraWarning, Args...>
             matcher { mozilla::Forward<Args>(args)... };
         return parser.match(mozilla::Move(matcher));
     }
+
 };
 
 } /* namespace frontend */
 } /* namespace js */
 
 #endif /* frontend_EitherParser_h */

--- a/js/src/frontend/TokenStream.cpp
+++ b/js/src/frontend/TokenStream.cpp
@@ -961,27 +961,35 @@ TokenStreamSpecific<CharT, AnyCharsAcces
                            args);
     }
 
     va_end(args);
 }
 
 template<typename CharT, class AnyCharsAccess>
 void
+TokenStreamSpecific<CharT, AnyCharsAccess>::errorAtVA(uint32_t offset, unsigned errorNumber, va_list *args)
+{
+    ErrorMetadata metadata;
+    if (computeErrorMetadata(&metadata, offset)) {
+        TokenStreamAnyChars& anyChars = anyCharsAccess();
+        ReportCompileError(anyChars.cx, Move(metadata), nullptr, JSREPORT_ERROR, errorNumber,
+                           *args);
+    }
+}
+
+
+template<typename CharT, class AnyCharsAccess>
+void
 TokenStreamSpecific<CharT, AnyCharsAccess>::errorAt(uint32_t offset, unsigned errorNumber, ...)
 {
     va_list args;
     va_start(args, errorNumber);
 
-    ErrorMetadata metadata;
-    if (computeErrorMetadata(&metadata, offset)) {
-        TokenStreamAnyChars& anyChars = anyCharsAccess();
-        ReportCompileError(anyChars.cx, Move(metadata), nullptr, JSREPORT_ERROR, errorNumber,
-                           args);
-    }
+    errorAtVA(offset, errorNumber, &args);
 
     va_end(args);
 }
 
 // We have encountered a '\': check for a Unicode escape sequence after it.
 // Return the length of the escape sequence and the character code point (by
 // value) if we found a Unicode escape sequence.  Otherwise, return 0.  In both
 // cases, do not advance along the buffer.

--- a/js/src/frontend/TokenStream.h
+++ b/js/src/frontend/TokenStream.h
@@ -1201,16 +1201,17 @@ class MOZ_STACK_CLASS TokenStreamSpecifi
     // TokenStream-specific error reporters.
     void reportError(unsigned errorNumber, ...);
 
     // Report the given error at the current offset.
     void error(unsigned errorNumber, ...);
 
     // Report the given error at the given offset.
     void errorAt(uint32_t offset, unsigned errorNumber, ...);
+    void errorAtVA(uint32_t offset, unsigned errorNumber, va_list* args);
 
     // Warn at the current offset.
     MOZ_MUST_USE bool warning(unsigned errorNumber, ...);
 
   private:
     // Compute a line of context for an otherwise-filled-in |err| at the given
     // offset in this token stream.  (This function basically exists to make
     // |computeErrorMetadata| more readable and shouldn't be called elsewhere.)