detect gigantoid matrices, and do nothing to avoid wacky overflows from float -> int

https://code.google.com/p/chromium/issues/detail?id=156231
Review URL: https://codereview.appspot.com/6842075

git-svn-id: http://skia.googlecode.com/svn/trunk@6513 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed