Add read only handles for the following predefined symbols

vm/symbols.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/symbols.h"
 
 #include "vm/handles.h"
 #include "vm/handles_impl.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
@@ skipping 245 matching lines @@
 
 
 RawString* Symbols::FromCharCode(int32_t char_code) {
   if (char_code > kMaxOneCharCodeSymbol) {
     return FromUTF32(&char_code, 1);
   }
   return predefined_[kNullCharId + char_code];
 }
 
 
+bool Symbols::IsPredefinedHandle(uword address) {
+  return predefined_handles_.IsValidScopedHandle(address);
+}
+
+
 void Symbols::GrowSymbolTable(const Array& symbol_table) {
   // TODO(iposva): Avoid exponential growth.
   intptr_t table_size = symbol_table.Length() - 1;
   intptr_t new_table_size = table_size * 2;
   Array& new_symbol_table = Array::Handle(Array::New(new_table_size + 1));
   // Copy all elements from the original symbol table to the newly allocated
   // array.
   String& element = String::Handle();
   dart::Object& new_element = Object::Handle();
   for (intptr_t i = 0; i < table_size; i++) {
@@ skipping 98 matching lines @@
 }
 
 
 RawObject* Symbols::GetVMSymbol(intptr_t object_id) {
   ASSERT(IsVMSymbolId(object_id));
   intptr_t i = (object_id - kMaxPredefinedObjectIds);
   return (i > 0 && i < Symbols::kMaxId) ? predefined_[i] : Object::null();
 }
 
 }  // namespace dart