CompositingPropertyUpdater should setNeedsGeometryUpdate

Prior to this CL, we set the needs geometry update bit on the enclosing
composited layer during style recalc. After this CL, CompositingPropertyUpdater
computes the needs geometry update bit as it walks down the tree. This change
is an improvement for two reasons:

1) The style system needs to know less about the compositing system. The style
   system just marks which RenderLayers have gone through a style change and
   the compositing system takes care of figuring out what parts of its state it
   needs to update.

2) This change is an incremental step towards making the needs geometry update
   bit work after layout. As it is walking down the tree, the
   CompositingPropertyUpdater is computing the absolute rects for each
   RenderLayer, which means it knows whether a RenderLayer moves during layout.
   In the future, we can be smart and set the needs geometry update bit after
   layout only if the RenderLayer actually moved.

Reorganizing the system also lets us cut off the upward propagation of the
needs geometry update bit because we no longer clear the bit during incremental
compositing updates.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/217323002

git-svn-id: svn://svn.chromium.org/blink/trunk@170366 bbb929c8-8fbe-4397-9dbb-9b2b20218538