Remove unnecessary repaint from line layout and cleanup logic

In the beforetime, it apparently made sense to use the cached repaint
rect from RenderLayer directly within line layout code to ensure we
got repainted. We now properly repaint ourself in this case without
having to rely on reaching directly into our layer for the info.

While I'm in the code, I'm moving the logic to mark ourself as
needing layout to ensure we trigger a repaint of ourself to
determineStartPosition (since it's responsible for marking the block
for full layout to begin with), and moving the hasInlineChild
optimization to LineLayoutState.

Review URL: https://codereview.chromium.org/145083009

git-svn-id: svn://svn.chromium.org/blink/trunk@165800 bbb929c8-8fbe-4397-9dbb-9b2b20218538