Merge a number of assertion failure fixes to the 3.0 branch.

test/mjsunit/regress/regress-1105.js

 // 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 18 matching lines @@
 // by the loaded file, and it should not fail an assertion in debug mode.
 
 __defineSetter__("x", function(){ throw 42; });
 
 try {
    this.eval('function x(){}');
    assertUnreachable();
 } catch (e) {
    assertEquals(42, e);
 }