Introduce some predicates over variable modes.

src/parser.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 561 matching lines @@
 
   bool inside_with() const { return top_scope_->inside_with(); }
   Scanner& scanner()  { return scanner_; }
   Mode mode() const { return mode_; }
   ScriptDataImpl* pre_data() const { return pre_data_; }
   bool is_extended_mode() {
     ASSERT(top_scope_ != NULL);
     return top_scope_->is_extended_mode();
   }
   Scope* DeclarationScope(VariableMode mode) {
-    return (mode == LET || mode == CONST_HARMONY)
+    return IsLexicalVariableMode(mode)
         ? top_scope_ : top_scope_->DeclarationScope();
   }
 
   // Check if the given string is 'eval' or 'arguments'.
   bool IsEvalOrArguments(Handle<String> string);
 
   // All ParseXXX functions take as the last argument an *ok parameter
   // which is set to false if parsing failed; it is unchanged otherwise.
   // By making the 'exception handling' explicit, we are forced to check
   // for failure at the call sites.
@@ skipping 285 matching lines @@
  private:
   static const int kTypeSlot = 0;
   static const int kElementsSlot = 1;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(CompileTimeValue);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PARSER_H_