Speed up some mjsunit test cases and clean up test expectations for arm and mips.

test/mjsunit/regress/regress-490.js

 // Copyright 2009 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 24 matching lines @@
 while (a.length < (2 << 11)) { a+= 'x'; }
 
 // Test specific for bug introduced in r3153.
 a.replace(/^(.*)/, '$1$1$1');
 
 // More generalized test.
 for (var i = 0; i < 10; i++) {
   var  b = '';
   for (var j = 0; j < 10; j++) {
     b += '$1';
+
+    // TODO(machenbach): Do we need all these replacements? Wouldn't corner
+    // cases like smallest and biggest suffice?
     a.replace(/^(.*)/, b);
   }
   a += a;
 }