Strip out most new-tab-animation code

Does not remove painting the favicon under the spinner under the same
experiment, since there's future exploration that'll likely end up
using it.

Bug: chromium:922614
Change-Id: Idc01d89bbc87f9872628e6205fc34e8303a972a5
Reviewed-on: https://chromium-review.googlesource.com/c/1416611
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623536}
7 files changed