Avoid an unitialized warning on linux.

Avoid an unitialized warning on linux.

Committed: https://code.google.com/p/skia/source/detail?r=7825

[Leon, 2013-02-21 23:14:12]

iY1 and iSubY give a warning that they may not be initialized, although they are
only used if s.doFilter, in which case they are initialized. Should we fix this?

[robertphillips, 2013-02-22 13:28:39]

I think so - lgtm.