Create specialized code stubs for PixelArray loads.

test/mjsunit/regress/regress-900966.js

 // Copyright 2008 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 19 matching lines @@
 assertEquals('abc'[10], 'x');
 
 // Test that the fast case character-at stub handles an out-of-bound
 // index correctly. We need to call the function twice to initialize
 // the character-at stub.
 function f() {
   assertEquals('abc'[10], 'x');
 }
 f();
 f();
+f();
+f();
 
 assertTrue(2[11] === undefined);
 Number.prototype[11] = 'y';
 assertEquals(2[11], 'y');
 
 assertTrue(true[12] === undefined);
 Boolean.prototype[12] = 'z';
 assertEquals(true[12], 'z');