Switch WebShare LayoutTests to the new Mojo JS bindings

This change rewrites the WebShare API layout tests to use the new Mojo
JS bindings.

Bug: 699569
Change-Id: Id95a016765c5b101ee347f760e7cec8b74ec4b7e
Reviewed-on: https://chromium-review.googlesource.com/587412
Reviewed-by: Yuzhu Shen <yzshen@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491079}
7 files changed