Speed up test importing by doing all the regex matching in a single pass.

This gives something like a 15x speedup over compiling and matching one
property at a time and doing multiple passes over the file.

R=ojan@chromium.org
BUG=268702

Review URL: https://chromiumcodereview.appspot.com/22350002

git-svn-id: svn://svn.chromium.org/blink/trunk@155647 bbb929c8-8fbe-4397-9dbb-9b2b20218538