We should explicitly set EGL_SURFACE_TYPE to EGL_DONT_CARE.
Otherwise, it's default value is EGL_WINDOW_BIT. However,
on some platforms, only EGL_PBUFFER_BIT is supported.
In this case, no matching config is found. So mWindowSurface
and mPbufferSurface will be nullptr. That's why we see
the bot failed.

Bug: chromium:1105208
Change-Id: I8ee2487fd24bab86a5ec22fbe7b8ff68081bc15c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2304429
Commit-Queue: Jiajia Qin <jiajia.qin@intel.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>