Fix SkXPSDevice

Fix SkXPSDevice

Make SkImageFilter parameter for SkXPSDevice::allowImageFilter const to match
the SkBitmapDevice base class.

BUG=skia:2097
R=senorblanco@chromium.org

Committed: https://code.google.com/p/skia/source/detail?r=13333

[Dominik Grewe, 2014-02-05 22:52:29]

Failed on the bots:
http://108.170.217.252:10117/builders/Test-Win7-ShuttleA-HD2000-x86_64-Debug/...

I compiled everything on my Mac using 'ninja -C out/Debug' (same for release)
and didn't get any error messages. Is there anything I can do to test this? Or
is it Windows specific? Maybe use a Windows try bot next time?

[Stephen White, 2014-02-05 23:15:50]

LGTM

[Dominik Grewe, 2014-02-05 23:16:33]

The CQ bit was checked by dominikg@chromium.org

[commit-bot: I haz the power, 2014-02-05 23:16:40]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/dominikg@chromium.org/156213002/120001

[commit-bot: I haz the power, 2014-02-05 23:16:42]

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

[commit-bot: I haz the power, 2014-02-05 23:16:43]

Presubmit check for 156213002-120001 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit ERRORS **
Since the CL is editing public API, you must have an LGTM from one of:
('reed@chromium.org', 'reed@google.com', 'bsalomon@chromium.org',
'bsalomon@google.com')

[Stephen White, 2014-02-05 23:23:42]

Committed patchset #4 manually as r13333.