Add test to validate eglGetPlatformDisplayEXT() Add a test to validate eglGetPlatformDisplayEXT() returns a valid display on devices that support the EGL extension EGL_EXT_platform_base. Bug: b/279980674 Test: EGLDisplayTest.GetPlatformDisplayEXT/* Change-Id: I8cbb9c3905deb960e567a07d64e6c9d590a4ae70 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6565328 Commit-Queue: Tim Van Patten <timvp@google.com> Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com>