D3D11: Fix mapBufferRange not invalidating static data. This was causing several dEQP tests with index data to fail. BUG=angleproject:1073 TEST=dEQP-GLES3.functional.buffer.map.read_write.render_as_index_array.* Change-Id: Ic231a561202fbcda499b7584905b80252a7407de Reviewed-on: https://chromium-review.googlesource.com/286772 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>