Bug 516338 - Improve typedef preservation

Besides the UX advantages of typedef preservation (such as refactorings
preserving typedefs), it's important for correctness because the
arguments of template aliases can be subject to SFINAE even if they
don't participate in the target type.

Change-Id: I4e71372553dc418d1b8c3e27bd2c0387a41a3269
4 files changed