The instance methods of the root class of an Objective-C hieararchy
can be messaged via the metaclass. Provide code completions for this
case. Fixes <rdar://problem/12560296>.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173903 91177308-0d34-0410-b5e6-96231b3b80d8