cpplint: Cleanup errors

Cleanup errors from upstream cpplint in preparation
for moving art's cpplint fork to upstream tip-of-tree cpplint.

Test: cd art && mm
Bug: 68951293
Change-Id: I15faed4594cbcb8399850f8bdee39d42c0c5b956
diff --git a/runtime/method_handles.h b/runtime/method_handles.h
index 8641918..930b8db 100644
--- a/runtime/method_handles.h
+++ b/runtime/method_handles.h
@@ -28,8 +28,8 @@
 namespace art {
 
 namespace mirror {
-  class MethodHandle;
-  class MethodType;
+class MethodHandle;
+class MethodType;
 }  // namespace mirror
 
 // Returns true if there is a possible conversion from |from| to |to|