Handle possibly NULL deref in comparison

Committed on behalf of groby@chromium.org

OCL=http://codereview.appspot.com/4633058/
CID=16790,16789

Review URL: http://codereview.appspot.com/4654049

git-svn-id: http://skia.googlecode.com/svn/trunk@1666 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed