44631 Improve MouseTracker lifecycle: Move checks to post-frame (a: desktop, a: tests, cla: yes, f: cupertino, f: gestures, f: material design, framework, severe: API break, waiting for tree to go green)

44682 Add textScaleFactor to SelectableText (cla: yes, f: material design, framework, waiting for tree to go green)

44856 gen_l10n.dart tool testing (a: internationalization, cla: yes, d: examples, f: cupertino, f: material design, team)

44923 iOS smart quote/dash configuration (a: text input, cla: yes, f: cupertino, f: material design, framework, platform-ios, waiting for tree to go green)