Skip unbinding the framebuffer on GLES1, where the function does not exist. This caused a crash when recording screenshots on native GLES1 implementations on Android. Bug: angleproject:5961 Change-Id: I7a35474154a4a8d56b36df02629944de7660dcd8 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2891567 Commit-Queue: Lubosz Sarnecki <lubosz.sarnecki@collabora.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com>
