Move some Cupertino colors to a common file. 

Create a CupertinoTabBar widget to mimic iOS looks

...and rearrange a bunch of code so that all these arguments/members
are always in the same order.

* expose debugPaintBaselinesEnabled

* Update binding.dart

review comments

I added a bunch of sample code to the core Widget subclasses so that
people would see that you are supposed to always include the `key`
argument.

* Let run default to first profile

* fix

* review notes

I added some tests for the bug that I fixed.
I added docs for IconButton and AppBar.
I added some new constructors for FractionalOffset.

This reverts commit 4a920557.

Does not yet migrate hasIdeviceId since that results in a cascade of
breaking interface changes that's significant enough for a separate
patch.

* Revert "Test installation status when ideviceid is not installed (#10254)"

This reverts commit 0e5d4a87.

* Revert "Partial rollback of #10204 (#10256)"

This reverts commit b291bf5d.

Ensure that flutter doctor returns a partial installation status when
ideviceid is not installed.

This broke Fuchsia as they haven't updated to Dart 1.24 yet :(

Our emulator detection was based on a simple heuristic that was
failing for the Samsung Galaxy S8. Any heuristic is flawed since
Android devices can report whatever they want to adb, but this
change attempts to tighten the detection by listing known models
(by their ro.hardware property). Again, these values could be
spoofed by emulator system images, but it's less likely to be
an issue than with our previous (and fall-back) heuristic.

Fixes #10203
Related: #10248

This helps to debug encoding issues that are believed to only happen for certain locales (see https://github.com/flutter/flutter/issues/10198 fo example).

DO NOT SUBMIT until Dart SDK has been bumped (https://github.com/flutter/flutter/pull/10110) as this depends on new API.

* Bump Dart SDK to `1.24.0-dev.3.0`.

* Fix (mega) gallery creation.

Maybe this will make the test work in the device lab...

Fixes https://github.com/flutter/flutter/issues/9377

Moved everything icons related except the material icon button and the materialicon font list to widget

* Remove '\n' from terminal input.

* Use trim instead of replaceAll

* Add unit test

* Cleanup the test

* Fixed lint

* Style adjustments

* Forgotten @override

* Revert "Forgotten @override"

Accidently added extra files.

This reverts commit 0aba24fc8ea321b3a4d0cd8aed7f589378393d96.

* Just @override change

Fixes #9062

This will help catch when we accidentally break --dartdocs.