Add PaintRectRecorder to BoxPainter::paintBoxDecorationBackgroundWithRect

This brings us down to 17 failures on fast/block with the SlimmingPaint flag on.

Review URL: https://codereview.chromium.org/649513005

git-svn-id: svn://svn.chromium.org/blink/trunk@184034 bbb929c8-8fbe-4397-9dbb-9b2b20218538