SkiaPerf is flagging a couple of recent performance regressions in the backdrop filter benchmark on iPhone 11.

https://flutter-flutter-perf.skia.org/e/?begin=1703159098&end=1707198160&keys=X7ab4563cac63a71fe20c1025b2c2403d&requestType=0&selected=commit%3D39142%26name%3D%252Carch%253Dintel%252Cbranch%253Dmaster%252Cconfig%253Ddefault%252Cdevice_type%253DiPhone_11%252Cdevice_version%253Dnone%252Chost_type%253Dmac%252Csub_result%253D90th_percentile_frame_rasterizer_time_millis%252Ctest%253Dbackdrop_filter_perf_ios__timeline_summary%252C&xbaroffset=39142

cc @gaaclarke