[CodeCompletion] Show protocol properties that are accessed through qualified id

This commit improves code completion for properties that are declared in
Objective-C protocols by making sure that properties show up in completions
when they are accessed through a qualified id.

rdar://24426041

Differential Revision: https://reviews.llvm.org/D25436

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@284007 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 86f83e0e3aa25579635770318b7344834be4bb6b)
2 files changed