Removed support.js

support.js was used by both sides of the iframe, so we need to avoid that somehow. It had only feature-detection for postMessage, and a user-agent-sniff for iOS. Moved the iOS-sniffing to inside rafPolyfill, since that's the only place it's needed. IE8 has support for postMessage, so we agreed to ignore IE7 for now and focus on fixing more important features first. Removed fallback-logic and related tests.
So now there's nothing left for support.js. Deleted.