GitLab

Synchronize hit-testing code with rendering code with regards to how the
coordinate space is handled (for userSpaceOnUse <clipPath>s), and how
the reference boxes is computed.

Also "straighten" out code-flow a bit while here.

BUG=418484
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2280963002
Cr-Commit-Position: refs/heads/master@{#414730}