Remove gpu support for willUseHWAALines.

Remove support in the gpu to use hardware AA lines. Current code paths could not reach this code and thus was never used.

The blend opt flag kDisableBlend should now be able to be removed, however it is left in this CL and will removed in its own.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/b414f25cf97a690034a180a2c704b4b3935b8ed0

[egdaniel, 2014-07-29 19:52:19]

Same removal of the HWAALines as before, but this time I did not remove the
DisableBlend flag yet. The couple try bots I've ran which failed in the initial
patch succeeded. I will try and figure out how removing the DisableBlend flag
was causing gm failures and remove it in a follow up cl

[egdaniel, 2014-07-29 19:52:19]

Same removal of the HWAALines as before, but this time I did not remove the
DisableBlend flag yet. The couple try bots I've ran which failed in the initial
patch succeeded. I will try and figure out how removing the DisableBlend flag
was causing gm failures and remove it in a follow up cl

[bsalomon, 2014-07-29 19:54:41]

lgtm

[egdaniel, 2014-07-29 20:01:14]

The CQ bit was checked by egdaniel@google.com

[commit-bot: I haz the power, 2014-07-29 20:01:45]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/egdaniel@google.com/427823002/40001

[commit-bot: I haz the power, 2014-07-29 20:15:54]

Change committed as b414f25cf97a690034a180a2c704b4b3935b8ed0