Linter should enforce Tests marked Slow or WontFix aren't allowed in TestExpectations

Tests marked Slow are only allowed in SlowTests,
Tests marked WontFix are only allowed in NeverFixTests,
These should not go into the TestExpectations file given there are
reserved files for them.

BUG=559390

Review URL: https://codereview.chromium.org/1491143003

Cr-Commit-Position: refs/heads/master@{#371179}
9 files changed