* 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
* Improve finders throughout toggle_buttons_test.dart
* Improve Material finders
* Update toggle_buttons_theme_test.dart finders to be more precise
* Refactor out textStyle and iconTheme finders
* Refactor iconTheme and buttonTextTheme logic
* 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.
