Added ability to lock strings to prevent their representation or encoding from changing.

src/handles.cc

 // Copyright 2011 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 924 matching lines @@
 
 
 bool CompileOptimized(Handle<JSFunction> function,
                       int osr_ast_id,
                       ClearExceptionFlag flag) {
   CompilationInfo info(function);
   info.SetOptimizing(osr_ast_id);
   return CompileLazyHelper(&info, flag);
 }
 
+
+void LockString(Handle<String> string) {
+  CALL_HEAP_FUNCTION_VOID(string->GetHeap()->isolate(),
+                          string->GetHeap()->LockString(*string));
+}
+
+
+StringLock::StringLock(Handle<String> string) : string_(string) {
+  LockString(string);
+}
+
+
+StringLock::~StringLock() {
+  string_->GetHeap()->UnlockString(*string_);
+}
+
 } }  // namespace v8::internal