Do not touch get() calls on 'this' object.

Summary:
These calls are part of the implementation of the smart pointer itself
and chaning it is likely to be wrong.
Example:
  T& operator*() const { return *get(); }

Reviewers: djasper

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D3540

llvm-svn: 207525