Fix the SSBO sync bug in two dispatch calls We should make sure that the raw buffer is the latest buffer before each dispatch call since the dispatch itself can update the raw buffer content. Bug: angleproject:3037 Change-Id: I75dddfd3e57b3c9cbcc58c02ed057c66cc8e1785 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1392379 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jiajia Qin <jiajia.qin@intel.com>