* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

* Themable elevation on dialogs.

* AlertDialogs Title/Content text styles

* Themable elevation on dialogs.

AlertDialogs Title/Content text styles

* finish merging change

* fixing tests

* Docs fixes

* Change const to final to fix analyzer errors

* Fix analyzer errors

* Remove dart:ui import

* Hans Comments

* Themable elevation on dialogs.

* Added `BackgroundColor` in widget + theme

* Addressing Comments

* Fix test name

* Add debugFillProperties test

* [Material] Add dialog theme.

* Address Hans' first round comments.

* Address Hans' Second round comments.

* Fix theme tests

* Address Will's comments, add golden test

* Update goldens

* Custom Border radius 16.0

* Address Hans' Comments

* Second round comments

* fix imports