Revert of Revert of Make drawImage a virtual on SkDevice

Revert of Revert of Make drawImage a virtual on SkDevice (patchset #1 id:1 of https://codereview.chromium.org/1124003002/)

Reason for revert:
retry now that some fixes (onDrawImage overrides) have landed in chrome/blink

Original issue's description:
> Revert of Make drawImage a virtual on SkDevice (patchset #4 id:60001 of https://codereview.chromium.org/1122643005/)
> 
> Reason for revert:
> speculative to see if it unblocks DEPS roll
> 
> Original issue's description:
> > Make drawImage a virtual on SkDevice
> > 
> > Now with patch for SkDeferredCanvas
> > 
> > This reverts commit 119468b71f8f4f45657ab30ead331be665de5a57.
> > 
> > BUG=skia:
> > 
> > Committed: https://skia.googlesource.com/skia/+/14fe8fd3e53b5e988aac189a8bc3ed28904d85c8
> 
> TBR=robertphillips@google.com,mtklein@google.com,reed@google.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/3538e3bfe2e00bc1b5b48d977fa7adff64d8c96b

TBR=robertphillips@google.com,mtklein@google.com,reed@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/620ba3afe09d4173c87537040fe50c1c1895fb1a

[reed1, 2015-05-06 14:54:09]

Created Revert of Revert of Make drawImage a virtual on SkDevice

[commit-bot: I haz the power, 2015-05-06 14:54:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1126273002/1

[commit-bot: I haz the power, 2015-05-06 14:54:42]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/620ba3afe09d4173c87537040fe50c1c1895fb1a

[reed1, 2015-05-06 17:15:20]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1127993004/ by reed@google.com.

The reason for reverting is: still breaking webglconformance.