Load elimination fix with a test case.

test/mjsunit/compiler/load-elimination.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 65 matching lines @@
 
 function test_transitioning_store2() {
   var b = new C();
   var a = new B(-1, 5);
   var f = a.x, g = a.y;
   b.x = 9;
   b.y = 11;
   return a.x + a.y;
 }
 
+var false_v = false;
+function test_transitioning_store3() {
+  var o = new C();
+  var v = o;
+  if (false_v) v = 0;
+  v.x = 20;
+  return o.x;
+}
+
 function killall() {
   try { } catch(e) { }
 }
 
 %NeverOptimizeFunction(killall);
 
 function test_store_load_kill() {
   var a = new B(1, 2);
   a.x = 4;
   var f = a.x;
@@ skipping 20 matching lines @@
   assertEquals(x, f());
   %OptimizeFunctionOnNextCall(f);
   assertEquals(x, f());
 }
 
 test(4, test_load);
 test(22, test_store_load);
 test(8, test_nonaliasing_store1);
 test(5, test_transitioning_store1);
 test(4, test_transitioning_store2);
+test(20, test_transitioning_store3);
 test(22, test_store_load_kill);
 test(7, test_store_store);