Use regular map-checks to guard string-length loading.

src/ast.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 442 matching lines @@
 void Property::RecordTypeFeedback(TypeFeedbackOracle* oracle,
                                   Zone* zone) {
   // Record type feedback from the oracle in the AST.
   is_uninitialized_ = oracle->LoadIsUninitialized(this);
   if (is_uninitialized_) return;
 
   is_monomorphic_ = oracle->LoadIsMonomorphicNormal(this);
   receiver_types_.Clear();
   if (key()->IsPropertyName()) {
     FunctionPrototypeStub proto_stub(Code::LOAD_IC);
-    StringLengthStub string_stub(Code::LOAD_IC, false);
-    if (oracle->LoadIsStub(this, &string_stub)) {
-      is_string_length_ = true;
-    } else if (oracle->LoadIsStub(this, &proto_stub)) {
+    if (oracle->LoadIsStub(this, &proto_stub)) {
       is_function_prototype_ = true;
     } else {
       Literal* lit_key = key()->AsLiteral();
       ASSERT(lit_key != NULL && lit_key->value()->IsString());
       Handle<String> name = Handle<String>::cast(lit_key->value());
       oracle->LoadReceiverTypes(this, name, &receiver_types_);
     }
   } else if (oracle->LoadIsBuiltin(this, Builtins::kKeyedLoadIC_String)) {
     is_string_access_ = true;
   } else if (is_monomorphic_) {
@@ skipping 713 matching lines @@
     OS::SNPrintF(buffer, "%d", Smi::cast(*value_)->value());
     str = arr;
   } else {
     str = DoubleToCString(value_->Number(), buffer);
   }
   return isolate_->factory()->NewStringFromAscii(CStrVector(str));
 }
 
 
 } }  // namespace v8::internal