* making flutter run work with gradle

* locate android studio

* add test for settings

* review comments

The appbar now scrolls off screen when you scroll the page far enough.

BUG=https://github.com/flutter/flutter/issues/4410

This reverts commit 6070cd94, reversing
changes made to d0f43ed9.

It broke the waterfall.

Update to latest Dart SDK (1.18.0-dev.4.2).

* update flutter run --devfs

* use async; add todo

Fixes https://github.com/flutter/flutter/issues/4407

Previously it wasn't included in the Runner target.

* Driver commands for controlling the Input widget

This commit introduces two new driver commands for controlling the
material Input widget.

* setInputText(SerializableFinder finder, String text)
* submitInputText(SerializableFinder finder)

Since it is not possible to directly modify the Input widget text,
these driver commands invokes the handler functions of the Input
widget: onChanged and onSubmitted, respectively. The `submitInputText`
command returns the submitted String as a result.

* Make input command handler methods private

Addressing comments from @yjbanov.

Simplify iOS template project

Fall back to the default xcodeproj if a workspace cannot be found

Remove dependency on FlutterAppDelegate so devs can more easily add SDKs.

When using flutter run, build the workspace instead of the project.

* configs for firebase hosting

* use the implicit FIREBASE_TOKEN

* don't print every command (lowers the chance of printing secret env vars, and for realz only deploy when merging into master

Previously adding the GridPaper caused us to lose all the state in our app. Now
we use a global key to keep our state.

Fixes #4648

Putting the opacity in the color is much faster than using an opacity
widget because the opacity widget creates an offscreen buffer.

Fixes #4651