PreParsing inner funcs: Do fewer variable name lookups.

src/ast/scopes.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_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/base/hashmap.h"
 #include "src/globals.h"
@@ skipping 16 matching lines @@
 class VariableMap: public ZoneHashMap {
  public:
   explicit VariableMap(Zone* zone);
 
   Variable* Declare(Zone* zone, Scope* scope, const AstRawString* name,
                     VariableMode mode, VariableKind kind,
                     InitializationFlag initialization_flag,
                     MaybeAssignedFlag maybe_assigned_flag = kNotAssigned,
                     bool* added = nullptr);
 
-  // Records that "name" exists but doesn't create a Variable. Useful for
-  // preparsing.
+  // Records that "name" exists (if not recorded yet) but doesn't create a
+  // Variable. Useful for preparsing.
   void DeclareName(Zone* zone, const AstRawString* name);
 
   Variable* Lookup(const AstRawString* name);
   void Remove(Variable* var);
   void Add(Zone* zone, Variable* var);
 };
 
 
 // Sloppy block-scoped function declarations to var-bind
 class SloppyBlockFunctionMap : public ZoneHashMap {
@@ skipping 824 matching lines @@
   void AllocateModuleVariables();
 
  private:
   ModuleDescriptor* module_descriptor_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_