Change wpt_expectations_updater to not depend on TestParser.
Background: In order to tell which tests to download -expected.txt files for and which tests to update expectations for, wpt-update-expectations checks the type of the test. Previously TestParser was used to do this, but I want to get rid of TestParser.
This CL replaces TestParser by checking whether a test is a ref tests by calling port.reference_files, which in turn checks the MANIFEST.json for tests in external/wpt.
Review-Url: https://codereview.chromium.org/2805563002
Cr-Commit-Position: refs/heads/master@{#463296}
2 files changed
