[builtins] Support SameValue and SameValueZero via runtime functions.

src/builtins.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/builtins.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 1785 matching lines @@
   return GetOwnPropertyKeys(isolate, args, SKIP_SYMBOLS);
 }
 
 
 // ES6 section 19.1.2.8 Object.getOwnPropertySymbols ( O )
 BUILTIN(ObjectGetOwnPropertySymbols) {
   return GetOwnPropertyKeys(isolate, args, SKIP_STRINGS);
 }
 
 
+// ES#sec-object.is Object.is ( value1, value2 )
+BUILTIN(ObjectIs) {
+  SealHandleScope shs(isolate);
+  DCHECK_EQ(3, args.length());
+  Object* value1 = args[1];

[Michael Starzinger, 2016/02/17 09:44:21]

nit: Even with the sealed handle scope, we should still be able to write this
code handlified (slots in the "args" object are implicit handles). I think that
would make it safer ...

  Handle<Object> value1 = args.at<Object>(1);

[Benedikt Meurer, 2016/02/17 10:20:26]

Done.

+  Object* value2 = args[2];
+  return isolate->heap()->ToBoolean(value1->SameValue(value2));
+}
+
+
 // ES6 section 19.1.2.11 Object.isExtensible ( O )
 BUILTIN(ObjectIsExtensible) {
   HandleScope scope(isolate);
   Handle<Object> object = args.atOrUndefined(isolate, 1);
   Maybe<bool> result =
       object->IsJSReceiver()
           ? JSReceiver::IsExtensible(Handle<JSReceiver>::cast(object))
           : Just(false);
   MAYBE_RETURN(result, isolate->heap()->exception());
   return isolate->heap()->ToBoolean(result.FromJust());
@@ skipping 2561 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8