Rename AncestorDependentProperties to CompositingInputs

This state on RenderLayer is specific to the compositor. The name
AncestorDependentProperties hasn't aged well. In other places, we call these
CompositingInputs, which seems more appropriate.

Review URL: https://codereview.chromium.org/322163003

git-svn-id: svn://svn.chromium.org/blink/trunk@175925 bbb929c8-8fbe-4397-9dbb-9b2b20218538