Now tests can be run from any directory. Location of test data is now determined using test file location provided by 'testcfg.py' script.

Tested under Linux, Mac, and Windows.

Review URL: http://codereview.chromium.org/155161


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2407 ce2b1a6d-e550-0410-aec6-3dcde31c8c00