62367 Make dartdoc warnings fatal (& cleanup of warnings) (a: accessibility, a: internationalization, a: tests, cla: yes, f: cupertino, f: material design, framework, team, waiting for tree to go green)

62668 Ensure dark theme is used when high contrast dark theme isn’t provided (a: accessibility, cla: yes, f: material design, framework, waiting for tree to go green)

62755 Add punctuation for unterminated sentences in doc comments (a: accessibility, a: internationalization, a: tests, cla: yes, d: api docs, documentation, f: cupertino, f: material design, framework, tool)

62788 Add onTertiaryTap* to TapGestureRecognizer and GestureDetector (a: accessibility, cla: yes, framework, waiting for tree to go green)