Fix LCD coverage regression in GrPorterDuffXPFactory

Fix LCD coverage regression in GrPorterDuffXPFactory

Fixes GrPorterDuffXPFactory to not use the blend table when getting
info about the LCD coverage XP.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/3e2d59ef36e1b9a63e524cf1b27d5f7bcfb5ff0b

[Chris Dalton, 2015-05-22 20:43:27]

cdalton@nvidia.com changed reviewers:
+ bsalomon@google.com, egdaniel@google.com

[bsalomon, 2015-05-22 20:49:42]

The CQ bit was checked by bsalomon@google.com

[bsalomon, 2015-05-22 20:49:43]

lgtm

[commit-bot: I haz the power, 2015-05-22 20:50:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149883004/20001

[commit-bot: I haz the power, 2015-05-22 20:51:15]

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

[commit-bot: I haz the power, 2015-05-22 20:51:16]

Try jobs failed on following builders:
  Build-Ubuntu-Clang-x86_64-Debug-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-Clang-x...)

[Chris Dalton, 2015-05-22 20:58:33]

The CQ bit was checked by cdalton@nvidia.com

[Chris Dalton, 2015-05-22 20:58:33]

The patchset sent to the CQ was uploaded after l-g-t-m from bsalomon@google.com
Link to the patchset: https://codereview.chromium.org/1149883004/#ps40001
(title: "clang warning")

[commit-bot: I haz the power, 2015-05-22 20:58:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1149883004/40001

[commit-bot: I haz the power, 2015-05-22 21:04:40]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/3e2d59ef36e1b9a63e524cf1b27d5f7bcfb5ff0b

[bungeman-skia, 2015-05-23 00:54:23]

A revert of this CL (patchset #3 id:40001) has been created in
https://codereview.chromium.org/1153803005/ by bungeman@google.com.

The reason for reverting is: Reverting this fix to revert
https://codereview.chromium.org/1124373002 .