Fix redundant index validation on the D3D9 backend Make sure that the computed index range is added to the cache of the main buffer object, instead of just to the static buffer object created for the buffer object. This applies to the code path used for D3D9. This way the front-end code in ValidateDrawElements gets the index range from the cache instead of having to iterate over all the indices used on every draw call. BUG=chromium:461274 TEST=WebGL conformance tests, angle_end2end_tests Change-Id: I07cf493d2771dab8e76d69bafda7ac49e5a04808 Reviewed-on: https://chromium-review.googlesource.com/262180 Reviewed-by: Olli Etuaho <oetuaho@nvidia.com> Tested-by: Olli Etuaho <oetuaho@nvidia.com>