In addition to the regression test I changed the gc-extension to take
a boolean flag specifying if compaction should be used (default is
false, existing tests will not change behaviour)

The regression test is disabled on arm and x64 with crankshaft
enabled. I made a bug to track this:
http://code.google.com/p/v8/issues/detail?id=1094


Review URL: http://codereview.chromium.org/6312118

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6619 ce2b1a6d-e550-0410-aec6-3dcde31c8c00