UBsan goes into an infinite recursion when __dynamic_cast instrumented with
"vptr". See crbug.com/609786.

Similar WebRTC change: https://codereview.webrtc.org/2983583002

BUG=None
TBR=fbarchard@chromium.org

Change-Id: Ia37635e639550d60f9a79df927447c7cfaacdc93
Reviewed-on: https://chromium-review.googlesource.com/671367
Commit-Queue: Henrik Kjellander <kjellander@chromium.org>
Reviewed-by: Henrik Kjellander <kjellander@chromium.org>