Get rid of compositing chicken-egg issues in a few places.

- CompositedLayerMapping::contentChanged (and hence RenderLayer::contentChanged since the latter
is the only caller of the former)
- All call sites of RenderLayerCompositor::updateLayerCompositingState other than RenderLayer::styleChanged

BUG=339892

Review URL: https://codereview.chromium.org/162353002

git-svn-id: svn://svn.chromium.org/blink/trunk@167466 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Reduce the number of parameters to LayoutStateMaintainer by one

Reduce the number of parameters to LayoutStateMaintainer by one.  I'm trying to
find ways to clean up some of the long parameter lists we have for various
methods in the render tree.  This is one such attempt.

BUG=None

Review URL: https://codereview.chromium.org/162613007

git-svn-id: svn://svn.chromium.org/blink/trunk@167467 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Reduce the number of virtual calls in the noOverflowRect() method by half

Reduce the number of virtual calls in the noOverflowRect() method by half.  I've
seen this method as fairly hot in some profile runs of layout and we're currently
calling the virtual verticalScrollbarWidth method twice.  This method is deeply
virtual in the sense that the two implementations of this method both call another
virtual method which in turn call yet another virtual method.  Mostly this is
awkward because the scrollbar code hasn't been de-abstracted since we've merged
into one platform.

BUG=none

Review URL: https://codereview.chromium.org/164773008

git-svn-id: svn://svn.chromium.org/blink/trunk@167468 bbb929c8-8fbe-4397-9dbb-9b2b20218538