Revert "Implement DeferredAnimatableValue"

This reverts commit 3d9f10fb57cc63ea5c96f092f67f8f517860c4e2 (https://codereview.chromium.org/19367002/)

Since we now take the snapshot values outside of the style resolve stage
we won't be needing DeferredAnimatableValue.

BUG=232273

Review URL: https://chromiumcodereview.appspot.com/22187002

git-svn-id: svn://svn.chromium.org/blink/trunk@155563 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Revert "Allow eviction of ImageBitmaps that are created from ImageElements."

This reverts commit cd89b4d0ecda08509f38b93c28fa06c899043279.
An ASSERT() hit the newly added MemoryCacheTest.DecodeCacheOrder

TBR=arbesfeld
BUG=259947, 166658

Review URL: https://codereview.chromium.org/22311005

git-svn-id: svn://svn.chromium.org/blink/trunk@155564 bbb929c8-8fbe-4397-9dbb-9b2b20218538