Call ImageImpl::destroy before destroying the image source. egl::Image destroys the source sibling before calling the backend destroy function. ImageVk needs the source image to do proper clean up. BUG=angleproject:3722 Change-Id: I110d77a9c4151166624bb953c579102ac7dab6ee Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1709752 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>