Fix BlitFramebuffer issues with large rects on iOS Enable adjustSrcDstRegionBlitFramebuffer workaround on iOS and fix a conflict when it is enabled in combination with clipSrcRegionBlitFramebuffer. Bug: angleproject:5417 Change-Id: I1de0f9f392643fbcf6900bad86d83084cb6d4009 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2601106 Reviewed-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com> Commit-Queue: James Darpinian <jdarpinian@chromium.org>