Currently WebAnimation::commitStyles() is rather inefficient as it sets new inline styles on a CSSStyleDeclaration as text, which requires serialization from the CSSValue and then parsing, and finally serializes the whole declaration before having it re-parsed once more when we call setAttribute("style", …). We should find a way to just pass around the CSSValue into the underlying data structures throughout.
Pull request: https://github.com/WebKit/WebKit/pull/4910
<rdar://problem/100943337>