Make --stress-compaction more stressful.

test/mjsunit/regexp-capture-3.js

 // Copyright 2012 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 131 matching lines @@
 no_last_match(function() { cons.replace("e", "E"); });
 
 
 // Here's one that matches once, then tries to match again, but fails.
 // Verify that the last match info is from the last match, not from the
 // failure that came after.
 "bar.foo baz......".replace(/(ba.).*?f/g, function() { return "x";});
 assertEquals("bar", RegExp.$1);
 
 
+// A test that initially does a zero width match, but later does a non-zero
+// width match.
 var a = "foo bar baz".replace(/^|bar/g, "");
 assertEquals("foo  baz", a);
 
 a = "foo bar baz".replace(/^|bar/g, "*");
 assertEquals("*foo * baz", a);