27734 [web] Code cleanup (cla: yes, platform-web)

27739 Prepare for updated avoid_classes_with_only_static_members lint (cla: yes, waiting for tree to go green, platform-web, needs tests)

27741 [web] Code cleanup (cla: yes, platform-web)

27766 [web] Code cleanup (cla: yes, platform-web)

27771 [web] Fixing clipping not being applied when height is zero (cla: yes, platform-web)

27774 [Keyboard] Send empty key events when no key data should  (affects: text input, cla: yes, platform-web, platform-windows)

27781 Use a pool for dart actions to avoid OOMs (cla: yes, platform-web)