* Theme provides all TextStyle properties

* match field declaration order in the test

* Theme.of returns text style with inherit == false

* change TextStyle.inherit logic; docs

* add TextStyle.debugLabel

* address comments

* add debug labels to Typography text styles

* optimize ThemeData: make it monomorphic, memoize result

* address comments

* RLU cache; fix text theme merging

* use FIFO cache for ThemeData; use HashMap to store inherited widgets

* address comments

* introduce localized text geometry in MaterialLocalizations

* remove geometry from color text themes

* fix merge conflict

* optional Localizations

* fix fallback; test; docs

Check ThemeData instead of Theme.

* Let Theme insert an IconTheme into the widget tree

* flip the order, no real reason

* Let icon theme use its own fallback

* review notes

* more review notes

* more widget const constructors

* prefer const constructors

* address review comments

* Scaffold appBar is-a PreferredSizeWidget, etc

* Updated

* Updated per review feedback

Aggressively apply the const lint.

...now that we have generic methods, their types need to be specified too.

Teach `paints` matches about `drawRect` and how to `paintChild`.

Also, improve test coverage.

The theme fallback mechanism was busted by the shadowThemeOnly change.

Fixes #6562