Relax requirement for instrumentation test runners.

Currently ADT checks that a specified instrumentation test runner
is actually a subclass of android.test.InstrumentationTestRunner.
This doesn't work for Google Instrumentation Test Runner since it
is a subclass of Google Instrumentation.

This CL relaxes the requirement that a runner has to implement
InstrumentationTestRunner: now it only has to implement
Instrumentation.

Fixes https://code.google.com/p/android/issues/detail?id=68575

Change-Id: I4500016941137bb98b90b5407c3e17d705ec2af9
1 file changed