Turn StringLengthStub (used by string wrappers only) into a hydrogen stub.

src/code-stubs-hydrogen.cc

 // Copyright 2012 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 590 matching lines @@
                              casted_stub()->is_inobject());
 }
 
 
 Handle<Code> LoadFieldStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 template<>
-HValue* CodeStubGraphBuilder<KeyedLoadFieldStub>::BuildCodeStub() {
-  return BuildLoadNamedField(GetParameter(0),
-                             casted_stub()->representation(),
-                             casted_stub()->offset(),
-                             casted_stub()->is_inobject());
+HValue* CodeStubGraphBuilder<StringLengthStub>::BuildCodeStub() {
+  HValue* string = BuildLoadNamedField(
+      GetParameter(0), Representation::Tagged(), JSValue::kValueOffset, true);
+  return BuildLoadNamedField(
+      string, Representation::Tagged(), String::kLengthOffset, true);
 }
 
 
-Handle<Code> KeyedLoadFieldStub::GenerateCode(Isolate* isolate) {
+Handle<Code> StringLengthStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 template <>
 HValue* CodeStubGraphBuilder<KeyedStoreFastElementStub>::BuildCodeStub() {
   BuildUncheckedMonomorphicElementAccess(
       GetParameter(0), GetParameter(1), GetParameter(2),
       casted_stub()->is_js_array(), casted_stub()->elements_kind(),
       STORE, NEVER_RETURN_HOLE, casted_stub()->store_mode());
@@ skipping 800 matching lines @@
   return BuildRegExpConstructResult(length, index, input);
 }
 
 
 Handle<Code> RegExpConstructResultStub::GenerateCode(Isolate* isolate) {
   return DoGenerateCode(isolate, this);
 }
 
 
 } }  // namespace v8::internal