Make browser hit testing return correct SurfaceId with nested Surfaces

A regression caused SurfaceHittest::GetTargetSurfaceAtPoint() to return
the incorrect SurfaceId when the correct Surface was nested more than
one layer from the root Surface. This fixes the regression.

BUG=589572
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1743303002

Cr-Commit-Position: refs/heads/master@{#378495}
5 files changed