Better codegen for '<expression> === void <literal>'.

test/cctest/test-api.cc

 // Copyright 2011 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 3844 matching lines @@
 
 
   ExpectBoolean("undetectable===null", false);
   ExpectBoolean("null===undetectable", false);
   ExpectBoolean("undetectable===undefined", false);
   ExpectBoolean("undefined===undetectable", false);
   ExpectBoolean("undetectable===undetectable", true);
 }
 
 
+THREADED_TEST(VoidLiteral) {
+  v8::HandleScope scope;
+  LocalContext env;
+
+  Local<v8::FunctionTemplate> desc =
+      v8::FunctionTemplate::New(0, v8::Handle<Value>());
+  desc->InstanceTemplate()->MarkAsUndetectable();  // undetectable
+
+  Local<v8::Object> obj = desc->GetFunction()->NewInstance();
+  env->Global()->Set(v8_str("undetectable"), obj);
+
+  ExpectBoolean("undefined == void 0", true);
+  ExpectBoolean("undetectable == void 0", true);
+  ExpectBoolean("null == void 0", true);
+  ExpectBoolean("undefined === void 0", true);
+  ExpectBoolean("undetectable === void 0", false);
+  ExpectBoolean("null === void 0", false);
+
+  ExpectBoolean("void 0 == undefined", true);
+  ExpectBoolean("void 0 == undetectable", true);
+  ExpectBoolean("void 0 == null", true);
+  ExpectBoolean("void 0 === undefined", true);
+  ExpectBoolean("void 0 === undetectable", false);
+  ExpectBoolean("void 0 === null", false);
+
+  ExpectString("(function() {"
+               "  try {"
+               "    return x === void 0;"
+               "  } catch(e) {"
+               "    return e.toString();"
+               "  }"
+               "})()",
+               "ReferenceError: x is not defined");
+  ExpectString("(function() {"
+               "  try {"
+               "    return void 0 === x;"
+               "  } catch(e) {"
+               "    return e.toString();"
+               "  }"
+               "})()",
+               "ReferenceError: x is not defined");
+}
+
 
 THREADED_TEST(ExtensibleOnUndetectable) {
   v8::HandleScope scope;
   LocalContext env;
 
   Local<v8::FunctionTemplate> desc =
       v8::FunctionTemplate::New(0, v8::Handle<Value>());
   desc->InstanceTemplate()->MarkAsUndetectable();  // undetectable
 
   Local<v8::Object> obj = desc->GetFunction()->NewInstance();
@@ skipping 10684 matching lines @@
   CHECK_EQ(v8_str("DONT_CHANGE"), obj->Get(v8_str("1")));
   obj->Set(v8_num(2), v8_str("DONT_CHANGE"), v8::ReadOnly);
   obj->Set(v8_num(2), v8_str("foobar"));
   CHECK_EQ(v8_str("DONT_CHANGE"), obj->Get(v8_num(2)));
 
   // Test non-smi case.
   obj->Set(v8_str("2000000000"), v8_str("DONT_CHANGE"), v8::ReadOnly);
   obj->Set(v8_str("2000000000"), v8_str("foobar"));
   CHECK_EQ(v8_str("DONT_CHANGE"), obj->Get(v8_str("2000000000")));
 }