Teach updateGraphicsLayerConfiguration about dirty bits

This CL teaches updateGraphicsLayerConfiguration about the needs to update
geometry dirty bit. There's no reason to update the graphics layer
configuration if nothing has changed about the composited layer mapping.

This CL also moves the computation of the update type to
clearNeedsGeometryUpdate to improve the parallelism between
updateCompositedBounds, updateGraphicsLayerConfiguration, and
updateGraphicsLayerGeometry.

We'll likely want to rename many of these concepts once we get closer to the
final design of the system.

Review URL: https://codereview.chromium.org/216763005

git-svn-id: svn://svn.chromium.org/blink/trunk@170391 bbb929c8-8fbe-4397-9dbb-9b2b20218538