Initialize InternalFormat::blendSupport.
Initialize InternalFormat::blendSupport.

Detected by the clang static analyzer.

Bug: angleproject:5008
Change-Id: I773c8219b0c7ff63a2a98edefc5bebab7a9aabd5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2416829
Reviewed-by: Courtney Goeltzenleuchter <aa371ec5c940a0ded89f7ed95bce84faebcf51df@google.com>
Reviewed-by: Jonah Ryan-Davis <682bdb9e7d8ba359ef169b8db374e7a99d394a46@google.com>
Commit-Queue: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle