Fix GetCurrentMethod to cope with callee-save frames.

We want to report something like this:

 Aborting because JNI app bug detected (see above for details)
              in call to Throw
              from Main.throwNullPointerException()V

Rather than something like this:

 Aborting because JNI app bug detected (see above for details)
              in call to Throw
              from java.lang.reflect.Method.$$$callee_save_method$$$()V

Change-Id: I84491c315dc0f114da1ab1fd9f191b5d04daf76e
diff --git a/src/thread.h b/src/thread.h
index 8fd0985..74e6f83 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -233,9 +233,7 @@
 
   // Returns the Method* for the current method.
   // This is used by the JNI implementation for logging and diagnostic purposes.
-  const Method* GetCurrentMethod() const {
-    return top_of_managed_stack_.GetMethod();
-  }
+  const Method* GetCurrentMethod() const;
 
   bool IsExceptionPending() const {
     return exception_ != NULL;