Fix bug where strings were not flattened before regexp.

src/objects-inl.h

 // Copyright 2006-2008 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 1413 matching lines @@
 uint32_t String::length_field() {
   return READ_UINT32_FIELD(this, kLengthOffset);
 }
 
 
 void String::set_length_field(uint32_t value) {
   WRITE_UINT32_FIELD(this, kLengthOffset, value);
 }
 
 
-void String::TryFlatten(StringShape shape) {
+Object* String::TryFlattenIfNotFlat(StringShape shape) {
   ASSERT(shape.type() == StringShape(this).type());
   // We don't need to flatten strings that are already flat.  Since this code
   // is inlined, it can be helpful in the flat case to not call out to Flatten.
   if (!IsFlat(shape)) {
-    Flatten(shape);
+    return TryFlatten(shape);
   }
+  return this;
 }
 
 
 uint16_t String::Get(StringShape shape, int index) {
   ASSERT(shape.type() == StringShape(this).type());
   ASSERT(index >= 0 && index < length(shape));
   switch (shape.full_representation_tag()) {
     case kSeqStringTag | kAsciiStringTag:
       return SeqAsciiString::cast(this)->SeqAsciiStringGet(index);
     case kSeqStringTag | kTwoByteStringTag:
@@ skipping 1043 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_