Move animation handling to Stack

This patch moves the remaining ChromeAnimation logic to the
StackLayout (the last place it is used). This allows us to start
simplifying the oversized Layout API.

Bug: 882508, 750381
Change-Id: I8b59cff1f8eb10777a524c078fadf008dec46542
Reviewed-on: https://chromium-review.googlesource.com/1217597
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590763}
2 files changed