Launch dangling markup mitigations for `\n` and `<` in URLs.

Intent to Remove: https://groups.google.com/a/chromium.org/d/msg/blink-dev/KaA_YNOlTPk/VmmoV88xBgAJ

Bug: 680970
Change-Id: I0aa854521376fd3ae7624b5b4359351709f17b41
Reviewed-on: https://chromium-review.googlesource.com/518156
Commit-Queue: Mike West <mkwst@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#475571}
4 files changed