17912 Fix units used in Linux shell timestamps. (cla: yes)

17913 Roll fuchsia/sdk/core/linux-amd64 from kEtiu… to kpECk… (cla: yes, waiting for tree to go green)

17914 Fix child caching in opacity_layer (cla: yes, perf: speed, severe: performance)

17915 Reland “Remove layer integral offset snapping” (cla: yes)

17916 Revert “[tracing] SceneDisplayLag is a synchronous event” (cla: yes)

17917 Roll src/third_party/dart b0d35855d88c..94178e920ee8 (37 commits) (cla: yes, waiting for tree to go green)