Fully check basis vectors for extent degeneracy.

The test for 'nearly singular matrix' in SkScalerContext::computeMatrices
is actually a check to see if anything will draw. Unfortunately, the
current test only checks when the a skew causes nothing to draw. This
adds the check for when the scale causes nothing to draw.

BUG=skia:4998
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1735613002

Review URL: https://codereview.chromium.org/1735613002
1 file changed