Reformat VVL error message Set messageContents1 and messageContents2 fields to nullptr, for ease of clean-up in follow-up changes. Make the extra properties fields more specific. Bug: angleproject:42265363 Bug: angleproject:415382790 Bug: angleproject:415383266 Change-Id: I032bc82c6aeb16281c868778db827318fa833005 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6496650 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Auto-Submit: Yuxin Hu <yuxinhu@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>