This patch works using a notification scheme - whenever a Texture or
Renderbuffer changes in such a way as to recreate its RenderTarget, we
pass a signal to the Framebuffer to invalidate some internal state.
Everything is entirely tracked in the Renderer11 layer, and the GL
layer is left untouched.

A RenderTarget11 now tracks points to which it is bound, and the
Framebuffer11 is mostly responsible for managing those links.

The three locations where we notify a Framebuffer when its bound
RenderTargets might be dirty are:

 1) RenderTarget11::~RenderTarget
 2) EGLImageD3D::copyToLocalRendertarget
 3) TextureStorage11_2D::useLevelZeroWorkaroundTexture

This patch gives about a 10% score increase in the D3D11 draw call
benchmark on my system.

BUG=angleproject:1260

Change-Id: Ide38aeadff4a2681bf5bd685e8ca3c9e2612a380
Reviewed-on: https://chromium-review.googlesource.com/327255Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>