Fix to prevent infinite recursion during AA clip generation

When path rendering is deferred, the GrInOrderDrawBuffer collects the paths and replays them. During path replaying an AA clip mask may need to be generated. If the AA clip mask generation code encounters a path that cannot be rendered on the gpu it uses the SW path rendering code. The SW path rendering code can then recursively kick off replaying of the stored paths - leading to an infinite loop. This patch short circuits potential loops by hiding the GrInOrderDrawBuffer while it is being replayed.

[TomH, 2012-05-03 16:26:47]

LGTM. Feels like we might be missing an opportunity to cache the recursive
mumblefrotz, but that's not important until it shows up in the profile.

[robertphillips, 2012-05-03 16:30:07]

committed as r3831