Implement proper map checks of captured objects.

test/mjsunit/compiler/escape-analysis.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
@@ skipping 155 matching lines @@
     assertEquals(4.5, o.f.d);
     assertEquals(5.9, o.e);
     assertEquals(6.7, o.g);
   }
   func(); func();
   %OptimizeFunctionOnNextCall(func);
   func(); func();
   delete deopt.deopt;
   func(); func();
 })();
+
+
+// Test map checks on captured objects.
+(function testMapCheck() {
+  var sum = 0;
+  function getter() { return 27; }
+  function setter(v) { sum += v; }
+  function constructor() {
+    this.x = 23;
+    this.y = 42;
+  }
+  function check(x, y) {
+    var o = new constructor();
+    assertEquals(x, o.x);
+    assertEquals(y, o.y);
+  }
+  var monkey = Object.create(null, {
+    x: { get:getter, set:setter },
+    y: { get:getter, set:setter }
+  });
+  check(23, 42); check(23, 42);
+  %OptimizeFunctionOnNextCall(check);
+  check(23, 42); check(23, 42);
+  constructor.prototype = monkey;
+  check(27, 27); check(27, 27);
+  assertEquals(130, sum);
+})();