Remove more vestigial CONST_LEGACY support and clean up var declaration code

src/runtime/runtime.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_RUNTIME_RUNTIME_H_
 #define V8_RUNTIME_RUNTIME_H_
 
 #include <memory>
 
 #include "src/allocation.h"
@@ skipping 447 matching lines @@
   F(RegExpInitializeAndCompile, 3, 1)          \
   F(RegExpExecMultiple, 4, 1)                  \
   F(RegExpExecReThrow, 4, 1)                   \
   F(IsRegExp, 1, 1)
 
 #define FOR_EACH_INTRINSIC_SCOPES(F)    \
   F(ThrowConstAssignError, 0, 1)        \
   F(DeclareGlobals, 3, 1)               \
   F(DeclareGlobalsForInterpreter, 3, 1) \
   F(InitializeVarGlobal, 3, 1)          \
-  F(InitializeConstGlobal, 2, 1)        \
   F(DeclareEvalFunction, 2, 1)          \
   F(DeclareEvalVar, 1, 1)               \
   F(NewSloppyArguments_Generic, 1, 1)   \
   F(NewStrictArguments, 1, 1)           \
   F(NewRestParameter, 1, 1)             \
   F(NewSloppyArguments, 3, 1)           \
   F(NewClosure, 1, 1)                   \
   F(NewClosure_Tenured, 1, 1)           \
   F(NewScriptContext, 2, 1)             \
   F(NewFunctionContext, 1, 1)           \
@@ skipping 651 matching lines @@
 
 class DeclareGlobalsEvalFlag : public BitField<bool, 0, 1> {};
 class DeclareGlobalsNativeFlag : public BitField<bool, 1, 1> {};
 STATIC_ASSERT(LANGUAGE_END == 3);
 class DeclareGlobalsLanguageMode : public BitField<LanguageMode, 2, 2> {};
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_RUNTIME_RUNTIME_H_