[SkSVGDevice] drawBitmap* support

Also fix a clip transform issue: clips are tracked in device space,
but if applied directly to leaf elements they are also subject to local
transforms ("transform='...'"). Instead, apply via <g> wrapper elements.

R=reed@google.com,mtklein@google.com

Review URL: https://codereview.chromium.org/959883003
2 files changed