Platform: Fix initialization order in tests. Because of the platform refactor in abf38572062b91 we broke the way the tests override the D3D workarounds for the tiny depth/stencil bug. This change passes a pointer to the platform directly in the EGL init logic, which solves this issue. It also removes all decltype code in the platform header which might fix the UBSAN problem we were seeing previously. Also change a present mode selection error into a warning in the Vk back-end, since this was being triggered on AMD, but is safe. BUG=angleproject:2042 Change-Id: Ibbd0c69ce11a840cf4b33c616f56020001e553aa Reviewed-on: https://chromium-review.googlesource.com/513519 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>