D3D: Fix not notifying RenderTarget release in TextureD3D This could lead to use-after-free for the RenderTarget object. Bug: chromium:1234829 Change-Id: I73d4547b8f09f2f2cf3f7f8394f7f573fe5a4ef5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3063858 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>