Convert editing/selection/move-vertically-with-padding-borders with selection_test

This patch converts the web test with selection_test() to promote usage
of W3C test harness, and also to ease the implementation of hit test
based up and down caret movements (http://bit.ly/2WB70oR).

Bug: 679977
Change-Id: Ia7d7186c4e1cb84b2b196fffa25a346718dbd97b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1559243
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#651184}
2 files changed