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

src/handles.h

Index: src/handles.h
diff --git a/src/handles.h b/src/handles.h
index 31be71459ae8ff868ef95fabba9df256f35c7a90..d5521f89c1e6ef43e49ecc2880e9c26876bc5e31 100644
--- a/src/handles.h
+++ b/src/handles.h
@@ -163,11 +163,9 @@ class HandleScope {
 
 // ----------------------------------------------------------------------------
 // Handle operations.
-// They might invoke garbage collection. The result is an handle to an
-// object of expected type, or the handle is a null handle if encountering
-// an internal error. Will not return a null handle due to out-of-memory
-// unless otherwise stated, but will instead try to do GC and die fatally
-// if that doesn't help.
+// They might invoke garbage collection. The result is an handle to
+// an object of expected type, or the handle is an error if running out
+// of space or encountering an internal error.
 
 void NormalizeProperties(Handle<JSObject> object,
                          PropertyNormalizationMode mode,
@@ -185,7 +183,7 @@ MUST_USE_RESULT Handle<NumberDictionary> NumberDictionarySet(
 void FlattenString(Handle<String> str);
 
 // Flattens a string and returns the underlying external or sequential
-// string. Never returns a null handle.
+// string.
 Handle<String> FlattenGetString(Handle<String> str);
 
 Handle<Object> SetProperty(Handle<JSReceiver> object,
@@ -381,22 +379,6 @@ class NoHandleAllocation BASE_EMBEDDED {
 #endif
 };
 
-
-// Prevents a (non-cons, non-slice) string from having its representation
-// changed. This is just a Handle based wrapper around Heap::LockString.
-// Use Heap::UnlockString to unlock (that one can't cause allocation, so
-// it doesn't need a Handle wrapper).
-void LockString(Handle<String> string);
-
-// Scoped lock on a string.
-class StringLock {
- public:
-  explicit StringLock(Handle<String> string);
-  ~StringLock();
- private:
-  Handle<String> string_;
-};
-
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_