--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -2136,17 +2136,17 @@ class ForOfLoopControl : public LoopCont
                 return false;
         }
 
         return true;
     }
 };
 
 BytecodeEmitter::BytecodeEmitter(BytecodeEmitter* parent,
-                                 const EitherParser<FullParseHandler>& parser, SharedContext* sc,
+                                 const EitherParser& parser, SharedContext* sc,
                                  HandleScript script, Handle<LazyScript*> lazyScript,
                                  uint32_t lineNum, EmitterMode emitterMode)
   : sc(sc),
     cx(sc->context),
     parent(parent),
     script(cx, script),
     lazyScript(cx, lazyScript),
     prologue(cx, lineNum),
@@ -2176,17 +2176,17 @@ BytecodeEmitter::BytecodeEmitter(Bytecod
     emitterMode(emitterMode),
     scriptStartOffsetSet(false),
     functionBodyEndPosSet(false)
 {
     MOZ_ASSERT_IF(emitterMode == LazyFunction, lazyScript);
 }
 
 BytecodeEmitter::BytecodeEmitter(BytecodeEmitter* parent,
-                                 const EitherParser<FullParseHandler>& parser, SharedContext* sc,
+                                 const EitherParser& parser, SharedContext* sc,
                                  HandleScript script, Handle<LazyScript*> lazyScript,
                                  TokenPos bodyPosition, EmitterMode emitterMode)
     : BytecodeEmitter(parent, parser, sc, script, lazyScript,
                       parser.errorReporter().lineAt(bodyPosition.begin),
                       emitterMode)
 {
     setScriptStartOffsetIfUnset(bodyPosition);
     setFunctionBodyEndPos(bodyPosition);

--- a/js/src/frontend/BytecodeEmitter.h
+++ b/js/src/frontend/BytecodeEmitter.h
@@ -215,17 +215,17 @@ struct MOZ_STACK_CLASS BytecodeEmitter
 
         EmitSection(JSContext* cx, uint32_t lineNum)
           : code(cx), notes(cx), lastNoteOffset(0), currentLine(lineNum), lastColumn(0),
             lastTarget{ -1 - ptrdiff_t(JSOP_JUMPTARGET_LENGTH) }
         {}
     };
     EmitSection prologue, main, *current;
 
-    EitherParser<FullParseHandler> parser;
+    EitherParser parser;
 
     PooledMapPtr<AtomIndexMap> atomIndices; /* literals indexed for mapping */
     unsigned        firstLine;      /* first line, for JSScript::initFromEmitter */
 
     uint32_t        maxFixedSlots;  /* maximum number of fixed frame slots so far */
     uint32_t        maxStackDepth;  /* maximum number of expression stack slots so far */
 
     int32_t         stackDepth;     /* current stack depth in script frame */
@@ -290,39 +290,39 @@ struct MOZ_STACK_CLASS BytecodeEmitter
     bool functionBodyEndPosSet;
 
     /*
      * Note that BytecodeEmitters are magic: they own the arena "top-of-stack"
      * space above their tempMark points. This means that you cannot alloc from
      * tempLifoAlloc and save the pointer beyond the next BytecodeEmitter
      * destruction.
      */
-    BytecodeEmitter(BytecodeEmitter* parent, const EitherParser<FullParseHandler>& parser,
+    BytecodeEmitter(BytecodeEmitter* parent, const EitherParser& parser,
                     SharedContext* sc, HandleScript script, Handle<LazyScript*> lazyScript,
                     uint32_t lineNum, EmitterMode emitterMode = Normal);
 
     template<typename CharT>
     BytecodeEmitter(BytecodeEmitter* parent, Parser<FullParseHandler, CharT>* parser,
                     SharedContext* sc, HandleScript script, Handle<LazyScript*> lazyScript,
                     uint32_t lineNum, EmitterMode emitterMode = Normal)
-      : BytecodeEmitter(parent, EitherParser<FullParseHandler>(parser), sc, script, lazyScript,
+      : BytecodeEmitter(parent, EitherParser(parser), sc, script, lazyScript,
                         lineNum, emitterMode)
     {}
 
     // An alternate constructor that uses a TokenPos for the starting
     // line and that sets functionBodyEndPos as well.
-    BytecodeEmitter(BytecodeEmitter* parent, const EitherParser<FullParseHandler>& parser,
+    BytecodeEmitter(BytecodeEmitter* parent, const EitherParser& parser,
                     SharedContext* sc, HandleScript script, Handle<LazyScript*> lazyScript,
                     TokenPos bodyPosition, EmitterMode emitterMode = Normal);
 
     template<typename CharT>
     BytecodeEmitter(BytecodeEmitter* parent, Parser<FullParseHandler, CharT>* parser,
                     SharedContext* sc, HandleScript script, Handle<LazyScript*> lazyScript,
                     TokenPos bodyPosition, EmitterMode emitterMode = Normal)
-      : BytecodeEmitter(parent, EitherParser<FullParseHandler>(parser), sc, script, lazyScript,
+      : BytecodeEmitter(parent, EitherParser(parser), sc, script, lazyScript,
                         bodyPosition, emitterMode)
     {}
 
     MOZ_MUST_USE bool init();
 
     template <typename Predicate /* (NestableControl*) -> bool */>
     NestableControl* findInnermostNestableControl(Predicate predicate) const;
 

--- a/js/src/frontend/EitherParser.h
+++ b/js/src/frontend/EitherParser.h
@@ -65,17 +65,17 @@ template<class Parser>
 struct GetParser
 {
     static Parser* get(Parser* parser) { return parser; }
 };
 
 template<class Parser>
 struct GetParseHandler
 {
-    static auto get(Parser* parser) -> decltype(&parser->handler) {
+    static frontend::FullParseHandler* get(Parser* parser) {
         return &parser->handler;
     }
 };
 
 template<class Parser>
 struct GetTokenStream
 {
     static auto get(Parser* parser) -> decltype(&parser->tokenStream) {
@@ -142,22 +142,22 @@ struct ErrorReporterMatcher
         return parser->tokenStream;
     }
 };
 
 } // namespace detail
 
 namespace frontend {
 
-template<class ParseHandler>
 class EitherParser
 {
-    mozilla::Variant<Parser<ParseHandler, char16_t>* const> parser;
+    // Leave this as a variant, to promote good form until 8-bit parser integration.
+    mozilla::Variant<Parser<FullParseHandler, char16_t>* const> parser;
 
-    using Node = typename ParseHandler::Node;
+    using Node = typename FullParseHandler::Node;
 
     template<template <class Parser> class GetThis,
              template <class This> class GetMemberFunction,
              typename... StoredArgs>
     using InvokeMemberFunction =
         detail::InvokeMemberFunction<GetThis, GetMemberFunction, StoredArgs...>;
 
   public: