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
Review URL: https://codereview.appspot.com/6416049

git-svn-id: http://skia.googlecode.com/svn/trunk@4687 2bbb7eff-a529-9590-31e7-b0007b416f81