These classes are responsible for actually running the tests, checking the results, generating visual diffs, etc.
Change-Id: I9b7f554409db1c97ac086c456db3aea3b993b5c6
It preloads the tests from the given path, runs them and asks for dumps and diffs. It will also prepare summaries in the future. It delegates
most of the work of actually running the individual tests to LayoutTest class and AbstractResult (and its subclasses in the future).
Change-Id: I483bf26a380b539e4769e61b4a09fa270ab0e8e9