Port the WebGL2 framebuffer-texture-changing-base-level test to native A nearly direct port of the https://www.khronos.org/registry/webgl/sdk/tests/conformance2/rendering/framebuffer-texture-changing-base-level.html test for easier debugging. BUG=angleproject:2291 Change-Id: Ibc8a7e77629f1ea3f15e92ea93f1210fa850c524 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1584361 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Shrek Shao <shrekshao@google.com>