64596 Fixes router to not report route information when it is already up to… (cla: yes, framework, waiting for tree to go green)

64599 Fix tests that use bogus objects, update TestImageInfo interface (cla: yes, f: cupertino, framework, waiting for tree to go green)

64621 migrate rendering to nullsafety (a: tests, cla: yes, framework, waiting for tree to go green)

64627 Slider and RangeSlider can be painted in a narrower constraint like other Material Wi… (cla: yes, f: material design, framework, waiting for tree to go green)

64652 Revert “Reland: Increase threshold for usage of compute for utf8 decoding on large strings to 50 KB” (cla: yes, framework, tool)

64668 Added support for lerpDuration() (cla: yes, framework, waiting for tree to go green)