* 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

* 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

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

Add Diagnosticable base class and documentation

Refactor RenderObject.toStringDeep and Widget.toStringDeep code to use DiagnosticsNode.

Mainly, this adds documentation to members that were previously
lacking documentation.

It also adds a big block of documentation about improving performance
of widgets.

This also removes some references to package:collection and adds
global setEquals and listEquals methods in foundation that we can use.
(setEquals in particular should be much faster than the
package:collection equivalent, though both should be faster as they
avoid allocating new objects.) All remaining references now qualify
the import so we know what our remaining dependencies are.

Also lots of code reordering in Flutter driver to make the code
consistent and apply the style guide more thoroughly.

This patch reworks some of the guts of scrolling to make it easier to
implement nested scrolling effects. The actually nested scrolling effect
will be included in a later patch.

* more widget const constructors

* prefer const constructors

* address review comments

Covers lib/ in package:flutter.

* Improved defaults for scroll view primary-ness

* Vertical scroll views default to primary:true.
* Horizontal scroll views default to primary:false.
* If a scroll view is primary and it got a non-null inherited primary
  scroll controller, it introduces a primary scroll controller inherited
  with a value of null for its descendants.

ScrollController now multiplexes writes to all registered positions;
reads of position continue to assert that only one position is
registered. Reads still require a single position.

Move the back button and drawer opening logic into the app bar.

Move the tap-status-bar-to-scroll-to-top logic to using
ScrollControllers. Provide a PrimaryScrollController and a `primary`
flag on scroll views.

Make it possible to track when a route becomes or stops being poppable.