* add missing trailing commas

* add more missing trailing commas

* add more and more missing trailing commas

* WIP

* Added tests and updated SafeArea implementation.

* Analyzer nits

* Review feedback

* Updated for SnackBar and PersistentFooterButton cases, added tests to check other potential spots.

* doc addition for SafeArea

* Typos

This PR introduces a number of changes and improvements to snack bars. This includes the ability to specify:

floating style of snack bars that adhere to the updated Material spec
elevation and shape on the SnackBar itself instead of relying on fixed values
a snackBarTheme as part of ThemeData which allows you to customize all of the above on an app-wide level.
This PR is includes the changes from #21484 as well as additional fixes and modifications. Thanks to @NikoYuwono for providing these changes and getting this off the ground!

* some space formattings

* always use blocks in if-else if a block is used

* format spaces in for and while

* allow multiline if conditions

* fix missing space

* fix indentof statements in BlockFunctionBody

* fix indentof statements in BlockFunctionBody in tests

* 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

* added test

* Future<void> main

* Future<void>.delayed

* prefer_void_to_Null

* address review comments

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

It was causing problems rolling Flutter into Fuchsia

* re-enable lint unnecessary_const

* remove trailling whitespaces

* remove unnecessary const (after merge)

* Changed duration

* Fixed column width for ios build error messages

* fixed a couple things

* fixed a couple things

* accidental changes

* added spaces

* added spaces

* Added test for default snackbar duration

* Fixed link:

* Final commit

* Final commit2

* Actual final commit

This reverts commit cc1cf13e.

This reverts commit 989f5741.

In a scaffold, snackbars are positioned above the BottomNavigationBar
and/or PersistentBottomButtons, if present. In such cases, they should
not apply bottom media padding to their widget sub-tree.

Applies any additional bottom, left, and right media padding inside the
snackbar, if present. This accounts for the iPhone X home indicator
widget and horizontal padding for the sensor housing notch in landscape
orientation.

* Notify the completer after the close animation completes on the snackbar

* Review comments

* Fix tests and analyzer warnings

* Fix analyzer warnings

* Manually fix every use of Point.x and Point.y

Some of these were moved to dx/dy, but not all.

* Manually convert uses of the old gradient API

* Remove old reference to Point.

* Mechanical changes

I applied the following at the root of the Flutter repository:

git ls-files -z | xargs -0 sed -i 's/\bPoint[.]origin\b/Offset.zero/g'
git ls-files -z | xargs -0 sed -i 's/\bPoint[.]lerp\b/Offset.lerp/g'
git ls-files -z | xargs -0 sed -i 's/\bnew Point\b/new Offset/g'
git ls-files -z | xargs -0 sed -i 's/\bconst Point\b/const Offset/g'
git ls-files -z | xargs -0 sed -i 's/\bstatic Point /static Offset /g'
git ls-files -z | xargs -0 sed -i 's/\bfinal Point /final Offset /g'
git ls-files -z | xargs -0 sed -i 's/^\( *\)Point /\1Offset /g'
git ls-files -z | xargs -0 sed -i 's/ui[.]Point\b/ui.Offset/g'
git ls-files -z | xargs -0 sed -i 's/(Point\b/(Offset/g'
git ls-files -z | xargs -0 sed -i 's/\([[{,]\) Point\b/\1 Offset/g'
git ls-files -z | xargs -0 sed -i 's/@required Point\b/@required Offset/g'
git ls-files -z | xargs -0 sed -i 's/<Point>/<Offset>/g'
git ls-files -z | xargs -0 sed -i 's/[.]toOffset()//g'
git ls-files -z | xargs -0 sed -i 's/[.]toPoint()//g'
git ls-files -z | xargs -0 sed -i 's/\bshow Point, /show /g'
git ls-files -z | xargs -0 sed -i 's/\bshow Point;/show Offset;/g'

* Mechanical changes - dartdocs

I applied the following at the root of the Flutter repository:

git ls-files -z | xargs -0 sed -i 's/\ba \[Point\]/an [Offset]/g'
git ls-files -z | xargs -0 sed -i 's/\[Point\]/[Offset]/g'

* Further improvements and a test

* Fix minor errors from rebasing...

* Roll engine

Aggressively apply the const lint.

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