Fix hit-testing of nested clip-paths with objectBoundingBox units

A nested clip-path should resolve against the original elements
reference box, but it would instead resolve against the referencing
Pass the appropriate reference box to SVGLayoutSupport::IntersectsClipPath.

Took the opportunity to export some related tests to WPT.

Bug: 938913
Change-Id: I6d6ad88f0a97028b21b1f1a488afbdd42a96264b
Reviewed-by: Stephen Chenney <>
Commit-Queue: Fredrik Söderquist <>
Cr-Commit-Position: refs/heads/master@{#638293}
12 files changed