Fix Xcode 4.x debugger build
Fix Xcode 4.x debugger build

Adding a mac_framework_dirs entry to help Xcode find the Qt frameworks.

R=djsollen@google.com

BUG=

Review URL: https://codereview.appspot.com/6564056

csulmone/skia,csulmone/skia,csulmone/skia,csulmone/skia