GitLab

Only allow frames who are ancestors of the drag_src_ to reset a drag_src_

Created layout test to show previous lack of dragend when moving iframe in dom as a result of dragging
Created layout test to verify lack of regression when frames containing drag source are moved/detached

Bug: 737691
Change-Id: Ic6cc8ac0528d35ac93a21612b453d6b3203a152d
Reviewed-on: https://chromium-review.googlesource.com/c/1265818
Commit-Queue: Darwin Huang <huangdarwin@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606276}