Adding new steps to Canvas unit test to validate that the deferred

Adding new steps to Canvas unit test to validate that the deferred
canvas state coherence test case passes with sequences of draw commands
that trigger flushes and purges of deferred draw commands.

This CL confirms that using SkGPipe fixes the deferred canvas issues that are 
the root problem of crbug.com/133432

BUG=https://code.google.com/p/chromium/issues/detail?id=133432
Committed: https://code.google.com/p/skia/source/detail?r=4687

[junov1, 2012-07-19 21:21:58]

PTAL

[Leon, 2012-07-19 21:45:19]

LGTM with spelling fixes.

https://codereview.appspot.com/6416049/diff/2001/tests/CanvasTest.cpp
File tests/CanvasTest.cpp (right):

https://codereview.appspot.com/6416049/diff/2001/tests/CanvasTest.cpp#newcode539
tests/CanvasTest.cpp:539: // that discards previously recorded commands. The
callenge is to maintain
challenge*

https://codereview.appspot.com/6416049/diff/2001/tests/CanvasTest.cpp#newcode561
tests/CanvasTest.cpp:561: // reset the recording session. The callenge is to
maintain correct
challenge*