Generate the egl Display extensions in Renderer9 and Renderer11. With the addition of EGL Image, the display extensions generated by Renderer9 and Renderer11 become significantly different. Instead of generating them via getXSupport() methods, generate them inside the renderers themselves. BUG=angleproject:970 Change-Id: Ib3fffabcca3e3cdef13ef994aa0b06dba0f00362 Reviewed-on: https://chromium-review.googlesource.com/293271 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>