Revert "Add workaround for flushing before readPixels." This reverts commit 46c13a15fa90130eca14301a4ef6deed12315037. Seems to have introduced significant flakiness on the Windows AMD FYI bot. Reverting while investigating. Change-Id: I9cfdb09a4a0d792a0c5db76c8b0b9d3285c0695a Reviewed-on: https://chromium-review.googlesource.com/280365 Tested-by: Kenneth Russell <kbr@chromium.org> Reviewed-by: Kenneth Russell <kbr@chromium.org>