Make VirtualTestSuites use a standard form of virtual/suitename/real/path/to/tests.

Eventually, when we do this for all virtual test suites, this will simplify the
logic around virtual test suites and will mean that people don't need to look
at the mapping the python code in order to understand which test a virtual
test corresponds to.

For now, convert all the ones that are easy. There are 3 left that use the
legacy naming scheme that are hard to move because they have platform baselines
spread in a bunch of directories.

Review URL: https://codereview.chromium.org/27054006

git-svn-id: svn://svn.chromium.org/blink/trunk@159606 bbb929c8-8fbe-4397-9dbb-9b2b20218538