Upstream scroll-boundary-behavior.html to wpt test.

This patch upstreams scroll_boundary_behavior.html to a web-platfrom-test. It
is currently a manual test. It asks users to perform some scroll/drag
behaviors and tap the "Done" button, and then checks the result.

Bug: 762054
Change-Id: I9be937341d5d95137c715b8111b557f09baf8a80
Reviewed-on: https://chromium-review.googlesource.com/653810
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Philip J├Ągenstedt <foolip@chromium.org>
Commit-Queue: Sandra Sun <sunyunjia@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501633}
2 files changed