Fix slow gm debug builds that are doing large path validation runs.

Add a new compile flag to allow path validation to be selectively
enabled instead of being always on.

Review URL: https://codereview.appspot.com/6734059

git-svn-id: http://skia.googlecode.com/svn/trunk@6036 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed