Start removing Current state

Now that we only write to current state from the main thread
we can actually just write directly in to drawing state and
avoid copying current to drawing state on each frame. simpleperf
on bouncing ball indicates this was saving around 8% CPU or so
per frame. As a next target we will eliminate the remaining work
in doTransaction and eliminate the doTransaction pass.

Test: Existing tests pass. simpleperf
Bug: 186200583
Change-Id: I59b75747d7371b3ffe870129c8be100c7daa6c4e