Make sure that names of temporaries do not clash with real variables.

src/scopes.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 171 matching lines @@
   // may have been added optimistically, but then only the variable name
   // was used (typically for labels). If the variable was not declared, the
   // addition introduced a new unresolved variable which may end up being
   // allocated globally as a "ghost" variable. RemoveUnresolved removes
   // such a variable again if it was added; otherwise this is a no-op.
   void RemoveUnresolved(VariableProxy* var);
 
   // Creates a new temporary variable in this scope.  The name is only used
   // for printing and cannot be used to find the variable.  In particular,
   // the only way to get hold of the temporary is by keeping the Variable*
-  // around.
+  // around.  The name should not clash with a legitimate variable names.
   Variable* NewTemporary(Handle<String> name);
 
   // Adds the specific declaration node to the list of declarations in
   // this scope. The declarations are processed as part of entering
   // the scope; see codegen.cc:ProcessDeclarations.
   void AddDeclaration(Declaration* declaration);
 
   // ---------------------------------------------------------------------------
   // Illegal redeclaration support.
 
@@ skipping 413 matching lines @@
   void SetDefaults(ScopeType type,
                    Scope* outer_scope,
                    Handle<ScopeInfo> scope_info);
 
   Zone* zone_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCOPES_H_