Fix a memory leak in skdiff that happens when the
directories do not contain the same files.

Only create the bitmaps when we need to use them.

Review URL: https://codereview.appspot.com/6850066

git-svn-id: http://skia.googlecode.com/svn/trunk@6481 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed