Revert "Fix for bug where composited rotate3d should SLERP instead of interpolating...

Revert "Fix for bug where composited rotate3d should SLERP instead of interpolating the axes and angles numerically."

This reverts commit 76ccfb05fe20d7c5007ceba84a011fc1453d621c.

https://codereview.chromium.org/1194073007/

Although the behavior is slightly different from the intended one as in CSS Transform Module Level 1, the original behavior before this patch is one that is more consistent when animation cancel happens.

However, the tests are relevant to checking when rotation starts or stops with a 0deg angle. It will be re-added as a separate patch to check for the correct behavior after the fix for blink rotate lands.

https://codereview.chromium.org/1279833006/

BUG=516577
R=ajuma@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1276813002

Cr-Commit-Position: refs/heads/master@{#342247}