Compute the correct GraphicsContext CTM while recording.

When recording, the recording canvas CTM does not reflect inherited
(parent canvas) transformations. We need to track these explicitly
to compute the correct getTotalMatrix() result.

For the current DisplayList clients (SVG masks/clips) this doesn't seem
to be an issue, but if we start using this mechanism for other
renderers, we need to not lie about the total matrix.

(as a side note, it is a shame that we have *any* getCTM() and
getTotalMatrix() users - maybe one day we can get rid of all of them)

The CL also turns on kUsePathBoundsForClip_RecordingFlag to speed up
record-time clipping.

R=schenney@chromium.org,senorblanco@chromium.org,eseidel@chromium.org

Review URL: https://codereview.chromium.org/67353003

git-svn-id: svn://svn.chromium.org/blink/trunk@162043 bbb929c8-8fbe-4397-9dbb-9b2b20218538