This consolidates all of the non-template .gitignore rules into the top level .gitignore, to ignore common things more broadly, with less maintenance needed for the .gitignore files. Does not touch the templates, so that they still produce needed .gitignores as part of flutter create.

* add an assert to validate the RefreshIndicator.onRefresh result

* add a test for RefreshIndicator.onRefresh assert

* switch to using FlutterError.reportError, FlutterErrorDetails, and FlutterError

This reverts commit e73d4061.

It caused major performance regressions.

This was fixed in #13150.

That commit rolled the engine to:
  flutter/engine@93b21795971357edbfd646f61b8d7f62388b0dae,

which rolled Dart to:
  dart-lang/sdk@70e5deacb54aea295665215837adaedd3d6a5bfa

which includes:
  dart-lang/sdk@d38c08d97358ebe4ee30e557bfee339dddda9b7a

Which fixes the breakage introduced in #13134.

This reverts commit f5d9c777.

This patch reorganises flutter_driver's lib/src directory into three
subdirectories:

* driver: sources transitively imported/exported by flutter_driver.dart,
  which defines the API used by driver tests executed on the host machine.

* extension: sources transitively imported/exported by
  driver_extension.dart, which defines the API used to instrument a
  Flutter app running on the target device for use with a driver test.

* common: sources common to both driver and extension code.

This makes rolling Flutter into repositories that use Bazel (or
Bazel-like build systems) significantly more robust, due to the simpler
glob patterns involved.

This is a bug in my previous CL: instead of cancelling the timer if
there are no more listeners, I canceled it if there were listeners (I
can claim I just missed a not :) ).

Not cancelling the timer when removing the last listener was not that bad, as
the timer callback is guarded by a check to see if there are listeners.
So the animation will not continue.

But in the case there were multiple listeners on the same stream, and
one of them is removed, this bug will stop the animation for all other
listeners.
I added a test case for this scenario.

Fix the dismissible demo in the gallery (make it actuall update when you pick something from its menu; give it a better affordance for resetting once you've dismissed everything).

Improve some docs.

Fix various flinging bugs with dismissible. Add tests for those cases.

Add a feature to flutter_test to support a drag-then-fling gesture (used by the flinging tests).

* feat: add optional headers params to network image

* fix: addressed comments

* feat: add test

* style: format code

* Add missing onDragCompleted to LongPressDraggable

* Add test for LongPressDraggable onDragStarted and onDragCompleted

Changed the ExpansionTile widget to have an optional value to
initialize the widget as collapsed or expanded.

The widget will be collapsed by default.

Use of this file was eliminated in e7657b94.

This fixes the popup menu code to do a better job of expanding
smoothly regardless of which side of the screen it's on. It still
results in a bidirection growth when positioned at the bottom of the
screen, so maybe we'll need to animate menus differently, but that's
a problem for another patch.

Also, improve some docs and provide RelativeRect.toSize which I needed
at one point while building this patch (though it didn't survive all
the way to the end).

* clear timeline events prior to starting a new action

* trailing commas

Fixes #12877 by reverting #9472

* AnimationController reset() method

Just a simple convenience method to fix #13039

* Added `reset()` test

* More test expectations

Per feedback.

* Removed test print

* Improved documentation of reset()

* Add controller.reverse to test

* Show Android tombstone during native crash

* Fix tombstone lines being missed on newer Android versions

This makes sure that we don't decode frames when we don't need to run
the animation.

For example, prior to this CL: an animated image in a page that is not
currently at the top of the page stack (it is covered by another page),
will keep the the image stream listener, and thus frames will still be
decoded.

* Add caching detail in doc

* review

This reverts commit 1abd8a12.

This allows `flutter run` to work on hosts that are IPv6-only.