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

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 522861deda05e2a163861ac527be202631387441..05af2cd2d8c68edafe6bdc2391fda89861e51896 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -2340,7 +2340,6 @@ bool Heap::CreateInitialObjects() {
   set_intrinsic_function_names(StringDictionary::cast(obj));
 
   if (InitializeNumberStringCache()->IsFailure()) return false;
-  if (InitializeStringLocks()->IsFailure()) return false;
 
   // Allocate cache for single character ASCII strings.
   { MaybeObject* maybe_obj =
@@ -2557,76 +2556,6 @@ MaybeObject* Heap::Uint32ToString(uint32_t value,
 }
 
 
-MaybeObject* Heap::LockString(String* string) {
-  ASSERT(!string->IsConsString());
-  FixedArray* locks = string_locks();
-  ASSERT(locks->length() > 1);
-  int length = locks->length();
-  int element_count = Smi::cast(locks->get(0))->value();
-  int element_index = element_count + 1;
-  if (element_index >= length) {
-    int new_length = length * 2;
-    MaybeObject* allocation = AllocateFixedArray(new_length);
-    FixedArray* new_locks = NULL;  // Initialized to please compiler.
-    if (!allocation->To<FixedArray>(&new_locks)) return allocation;
-    for (int i = 1; i < length; i++) {
-      new_locks->set(i, locks->get(i));
-    }
-    set_string_locks(new_locks);
-    locks = new_locks;
-  }
-  locks->set(element_index, string);
-  locks->set(0, Smi::FromInt(element_index));
-  return string;
-}
-
-
-void Heap::UnlockString(String* string) {
-  FixedArray* locks = string_locks();
-  ASSERT(locks->length() > 1);
-  int element_count = Smi::cast(locks->get(0))->value();
-  ASSERT(element_count > 0);
-  ASSERT(element_count < locks->length());
-  for (int i = 1; i <= element_count; i++) {
-    String* element = String::cast(locks->get(i));
-    if (element == string) {
-      if (i < element_count) {
-        locks->set(i, locks->get(element_count));
-      }
-      locks->set_undefined(element_count);
-      locks->set(0, Smi::FromInt(element_count - 1));
-      return;
-    }
-  }
-  // We should have found the string. It's an error to try to unlock
-  // a string that hasn't been locked.
-  UNREACHABLE();
-}
-
-
-bool Heap::IsStringLocked(String* string) {
-  if (string->IsConsString()) return false;
-  FixedArray* locks = string_locks();
-  ASSERT(locks->length() > 1);
-  int element_count = Smi::cast(locks->get(0))->value();
-  for (int i = 1; i <= element_count; i++) {
-    if (locks->get(i) == string) return true;
-  }
-  return false;
-}
-
-
-MaybeObject* Heap::InitializeStringLocks() {
-  const int kInitialSize = 6;
-  MaybeObject* allocation = AllocateFixedArray(kInitialSize);
-  if (allocation->IsFailure()) return allocation;
-  FixedArray* new_array = FixedArray::cast(allocation->ToObjectUnchecked());
-  new_array->set(0, Smi::FromInt(0));
-  set_string_locks(new_array);
-  return new_array;
-}
-
-
 Map* Heap::MapForExternalArrayType(ExternalArrayType array_type) {
   return Map::cast(roots_[RootIndexForExternalArrayType(array_type)]);
 }