Avoid strict-aliasing problems with Handles.

Replace use of reinterpret_cast with down_cast.

Bug: 18074773

Change-Id: Id42d462f2798f69a2210e5912f441c868b8b5812
(cherry picked from commit b5cb18a116dce45fc077b3f5b94af9e521e79e8d)
2 files changed