This allows us to skip calling the dynamic shader generation and
program shader application when there haven't been any state
changes. It builds on the previous work that immediately update
state caches in the VertexArray11 and Framebuffer11. It should
improve performance in draw-call limited applications by a small
margin.

For reference, here are the conditions under which the shaders
are refreshed:

1. Directly changing the program executable
2. The vertex attribute layout
3. The fragment shader's rendertargets
4. Enabling/disabling rasterizer discard
5. Enabling/disabling transform feedback
6. An internal shader was used
7. Drawing with/without point sprites

Improves the score of the draw call stress test for the D3D11
back-end (with null driver) by about 40% on my test machine.

The 9_3 back-end seems to have an issue where the getSRV call
to a texture storage can change the "use level zero workaround"
status of the storage, which in turn will invalidate the state.
Since this is localized to 9_3 only, put in a hack to disable
an assert check for now.

BUG=angleproject:2151

Change-Id: Idbd0a31376691b33972e735d5833a9b02a8a4aa9
Reviewed-on: https://chromium-review.googlesource.com/666278Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>