[Typed OM] Implement CSSValue->CSSRotation conversion

The other TransformComponents
(CSSMatrixTransformComponent, CSSPerspective, CSSScale, CSSSkew,
CSSTranslation) just return nullptr for now.

BUG=545318

Review-Url: https://codereview.chromium.org/2039093003
Cr-Commit-Position: refs/heads/master@{#402267}
4 files changed