Remove MethodHelper from the interpreter.

Use ShadowFrame to get the executing method to avoid a handle for the current
method.
Various associated bits of header file clean-up and removal of an unnecessary
use of MethodHelper in CompilerDriver.

Change-Id: I3b6f4413701e8fc6b0c58b0041a0dd15472bedaa
diff --git a/runtime/reflection.h b/runtime/reflection.h
index f9a7951..1764774 100644
--- a/runtime/reflection.h
+++ b/runtime/reflection.h
@@ -65,7 +65,7 @@
     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
 void InvokeWithShadowFrame(Thread* self, ShadowFrame* shadow_frame, uint16_t arg_offset,
-                           MethodHelper* mh, JValue* result)
+                           JValue* result)
     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
 jobject InvokeMethod(const ScopedObjectAccessAlreadyRunnable& soa, jobject method, jobject receiver,