Fix a Field.isAnnotationPresent crash.

For instances of Proxy, generated at runtime, there is no corresponding
.dex file.

Bug: https://code.google.com/p/android/issues/detail?id=24846
Change-Id: I36da43d5279a61b8cb71cdf2bbc3065b6a979830
Remove stray references to non-existent opcodes.

Change-Id: I83ca6ea12344a8df7ef14d600baf5060b76870f5
Fix a tracked reference leak in dvmGenerateProxyClass.

Bug: https://code.google.com/p/android/issues/detail?id=43919
Change-Id: Ib5c217368ba75f4422d0c932c2c67daaaeddea4b