Re-land "Move Uniform and UBO info to the gl::Program layer." This data was previously stored entirely in the Impl level. Move as much as possible to the GL level, using a read-only view in the Impl level. Some information in D3D-specific, and should be stored separately in the Impl. This patch has a lot of refactoring that splits the D3D and GL info, and moves as much validation as possible to the GL layer, where it is shared between the back-ends. Re-land with fix for dEQP unused uniforms. The fix involves storing a local copy of all uniform data in the GL layer. This will also let us validate sampler indexes during draw calls at the GL layer. BUG=angleproject:1123 TEST=end2end_tests,Canary WebGL (D3D11/GL), dEQP-GLES2+3.functional.uniform_api Change-Id: I9074c057c2c67d4d3221ec11c5556a26e07c7ceb Reviewed-on: https://chromium-review.googlesource.com/297070 Tryjob-Request: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>