DM::SKPSrc::size() reports correct size.

DM::SKPSrc::size() reports correct size.

Also:
  DM::GPUSink and DM::RasterSink crop DM::Src::size()
  SkPictureData::GetCullRect(SkStream*, SkRect*) function

Motivation:
  Improve PDF testing by printing the entire SKP.

BUG=skia:3365

[hal.canary, 2015-01-28 18:20:51]

The CQ bit was checked by halcanary@google.com

[hal.canary, 2015-01-28 18:21:19]

halcanary@google.com changed reviewers:
+ mtklein@google.com

[hal.canary, 2015-01-28 18:21:31]

ptal

[commit-bot: I haz the power, 2015-01-28 18:21:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/863243004/1

[commit-bot: I haz the power, 2015-01-28 18:21:46]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-01-29 00:21 UTC

[mtklein, 2015-01-28 19:01:05]

Counterproposal:
https://codereview.chromium.org/863243005

[commit-bot: I haz the power, 2015-01-29 00:21:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-29 00:21:50]

No LGTM from a valid reviewer yet. Please ask for an LGTM from a
full Skia committer from
https://skia.googlesource.com/skia/+/master/CQ_COMMITTERS