Remove flushes

Dependent upon http://codereview.appspot.com/6465061/ landing first

[bsalomon, 2012-08-16 21:42:35]

Removes some unnecessary GrContext flush() calls. Also, makes morphology and
convolution play nice with the IODB. They were just drawing direct to the GrGpu.
Now they use prepareToDraw() which would flush the IODB to the GrGpu were it to
return the GrGpu. However, in the default build it'll be the IODB that is
returned.

http://codereview.appspot.com/6446150/diff/4001/include/gpu/GrContext.h
File include/gpu/GrContext.h (left):

http://codereview.appspot.com/6446150/diff/4001/include/gpu/GrContext.h#oldco...
include/gpu/GrContext.h:887: GrAssert(1 == temp->getRefCnt());
It looks like we're assuming that the user of the scratch texture didn't put it
into the IODB (which will grab a ref). That doesn't seem right. Is the assert
just bogus?

[bsalomon, 2012-08-17 13:40:39]

I removed the assertions after confirming with Rob that they are incorrect.

[robertphillips, 2012-08-17 13:50:04]

LGTM

[TomH, 2012-08-17 13:52:13]

LGTM

http://codereview.appspot.com/6446150/diff/1003/include/gpu/GrContext.h
File include/gpu/GrContext.h (right):

http://codereview.appspot.com/6446150/diff/1003/include/gpu/GrContext.h#newco...
include/gpu/GrContext.h:781: // Sets the paint and returns the target to draw
into. The paint can be NULL
Nit: if you use ///, doxygen will see it.

[bsalomon, 2012-08-17 14:07:06]

Landed in r5150.