Fix CSSPreloadScanner to avoid missing rules

This fixes a couple of bugs with the CSSPReloadScanner that made it miss
rules in which the URL wasn't quoted or the rule didn't end with a
semicolon. It also adds tentative WPT tests for that functionality, as
the tests are also relevant for WebKit.

Bug: 903785
Change-Id: I6d7dae1db3617184148fd71dfdb62fa1ee19e74f
Reviewed-on: https://chromium-review.googlesource.com/c/1331042
Commit-Queue: Yoav Weiss <yoavweiss@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610744}
7 files changed