Change LookupForWrite to always do a full lookup and check the result.

test/mjsunit/regress/readonly4.js

 // Copyright 2013 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
 //       with the distribution.
 //     * Neither the name of Google Inc. nor the names of its
 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#include "v8.h"
+var slow = {};
+var p = {};
 
-#include "cctest.h"
+slow.__proto__ = p;
+slow.x = 10;
+slow.y = 10;
+Object.defineProperty(p, "x", {writable:false, value:5});
 
-using namespace v8;
+function c(p) {
+  return {__proto__: p};
+}
 
-// This test fails if properties on the prototype of the global object appear
-// as declared globals.
-TEST(StrictUndeclaredGlobalVariable) {
-  HandleScope scope(Isolate::GetCurrent());
-  v8::Local<v8::String> var_name = v8_str("x");
-  LocalContext context;
-  v8::TryCatch try_catch;
-  v8::Local<v8::Script> script = v8_compile("\"use strict\"; x = 42;");
-  v8::Handle<v8::Object> proto = v8::Object::New();
-  v8::Handle<v8::Object> global =
-      context->Global()->GetPrototype().As<v8::Object>();
-  proto->Set(var_name, v8_num(100));
-  global->SetPrototype(proto);
-  script->Run();
-  CHECK(try_catch.HasCaught());
-  v8::String::Utf8Value exception(try_catch.Exception());
-  CHECK_EQ("ReferenceError: x is not defined", *exception);
+function s(v) {
+  return v.x = 1;
 }
+
+function s_strict(v) {
+  "use strict";
+  v.x = 1;
+}
+
+var o1 = c(slow);
+var o2 = c(slow);
+var o1_strict = c(slow);
+var o2_strict = c(slow);
+var o3 = c(slow);
+var o4 = c(slow);
+
+// Make s slow.
+// Do this after using slow as prototype, since using an object as prototype
+// kicks it back into fast mode.
+delete slow.y;
+
+s(o1);
+s(o2);
+s_strict(o1_strict);
+s_strict(o2_strict);
+
+delete slow.x;
+// Directly setting x should fail.
+o3.x = 20
+assertEquals(5, o3.x);
+
+// Setting x through IC should fail.
+s(o4);
+assertEquals(5, o4.x);
+assertThrows("s_strict(o4);", TypeError);