only take the vertical special-case for gradients when dx is exactly 0, as a
zoomed gradient can have a very small dx, but be no where near to vertical.

http://code.google.com/p/skia/issues/detail?id=1101
Review URL: https://codereview.appspot.com/7310059

git-svn-id: http://skia.googlecode.com/svn/trunk@7653 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed