* implicit-casts:false in flutter/lib/src/material

* address review comments

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

* make BuildContext.{ancestorStateOfType,ancestorRenderObjectOfType,rootAncestorStateOfType} generic

* make BuildContext.inheritFromWidgetOfExactType generic

* make BuildContext.ancestorInheritedElementForWidgetOfExactType generic

* make BuildContext.ancestorWidgetOfExactType generic

* fix snippet

* bump scoped_model on temp version

* update names

* Revert "bump scoped_model on temp version"

This reverts commit d1fcbba028cdb07f44738d1652391692d1ea5ec0.

* address review comments

* fix ci

* address review comments

* repeat the deprecation notice

* fix uppercase

* use of recommanded deprecation syntax

* address review comment

* Update constructor APIs TooltipTheme, ToggleButtonsTheme, PopupMenuTheme
The constructor signatures for TooltipTheme, ToggleButtonsTheme, PopupMenuTheme have been incompatibly changed. They now require just one theme data parameter.

* Add margin parameter to tooltips

* Improve tooltip tests to find the tooltip's `Container` instead of arbitrary number of parent calls

* Implement TooltipThemeData and TooltipTheme

* Add text style property 

* Updated tooltip default colors for light and dark theme to match Material specification

Revert "[Material] Implement TooltipTheme and Tooltip.textStyle, fix Tooltip debugLabel, update Tooltip defaults (#36030)" (#36851)

This reverts commit 62158a1b.

[Material] Implement TooltipTheme and Tooltip.textStyle, fix Tooltip debugLabel, update Tooltip defaults (#36030)

* Implement TooltipThemeData and TooltipTheme

* Add tooltip text style property

* Update default tooltip text style and decoration to match Material specification

* Fix debugLabel incorrectly labeling "white" as "black", and vice versa by default