Pass binding enum to Framebuffer::syncState. Will allow us to determine if we're clearing the read or draw FBO. Then we can stash clears for the draw FBO only and issue them immediately for the read FBO in the Vulkan back-end. Bug: angleproject:4517 Change-Id: Ifc043317d6156a75749b13f9d2c44a17e14ee378 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2139997 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>