[builtins] Support SameValue and SameValueZero via runtime functions.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index 1c596503ef86e95bf3b6e3054ade3c484ae4a661..daaa5be112c89be3ecb01102626766030d616148 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -1803,6 +1803,16 @@ BUILTIN(ObjectGetOwnPropertySymbols) {
 }
 
 
+// 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);