Implement a part of two-way sync logic for WPT WebDriver tests.

Create a TestExpectation file and implement the logic where webdriver runner is
able to read and compare existing expectations with test results.

Bug: 881513
Change-Id: Ib829eed2c90223d1d861de460f3b0477b37befc9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1478932
Reviewed-by: John Chen <[email protected]>
Reviewed-by: Robert Ma <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Philip Jägenstedt <[email protected]>
Commit-Queue: Kyle Ju <[email protected]>
Cr-Commit-Position: refs/heads/master@{#645361}
6 files changed