Fix reg type merging in the verifier

Fixes bad merging of float, long and double reg types with constant types. Adds
merging tests in reg_type_test.

Bug: https://code.google.com/p/android/issues/detail?id=66434
Bug: 13464407
Change-Id: I56761f5f5562b742d0ef9cc66b58d55f7b668949
3 files changed