Move logic of InvalidateFramebuffer to Framebuffer.cpp. This method will translate to an implementation call. BUG=angle:732 Change-Id: Ida1e3c9cccd94f7d166cc9a785708c12bfc52da5 Reviewed-on: https://chromium-review.googlesource.com/213853 Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Brandon Jones <bajones@chromium.org> Reviewed-by: Shannon Woods <shannonwoods@chromium.org>