Also, correct an existing test description.

Applies comments I missed from https://github.com/flutter/flutter/pull/10904.

* Prefix and Suffix support for TextFields

* Adding Tests

* Removing spurious newline.

* Fixing a small problem with the test

* Code review changes

* Code Review Changes

* Review Changes

* Export the new StrokeJoin enum

* Added example for line styles, and enabled line join styles.

* Reverting inadvertent change to main.dart.

* Updated due to code review of engine code

* Removed example.

...so that we can compare it to the not-working test next to it.

1. Run all Xcode tool invocations through ProcessManager, which allows
us to mock out failures, etc. for tests.

2. Add said tests.

This reverts commit 3e265e9e.

Rather than pre-compute Xcode install path, version, and EULA status,
compute and cache on demand.

This reverts commit bb8e2a7c.

Triggers a doctor failure on the Mac chromebots.

Rather than pre-compute Xcode install path, version, and EULA status,
compute and cache on demand.

Picks up primarily stability fixes.

* Provide haptic/acoustic feedback for tap & long-press on Android

* review comments

* fixed example code

* review comments

* comment fix

The main purpose of this PR is to make it so that when you set the
initial route and it's a hierarchical route (e.g. `/a/b/c`), it
implies multiple pushes, one for each step of the route (so in that
case, `/`, `/a`, `/a/b`, and `/a/b/c`, in that order). If any of those
routes don't exist, it falls back to '/'.

As part of doing that, I:

 * Changed the default for MaterialApp.initialRoute to honor the
   actual initial route.

 * Added a MaterialApp.onUnknownRoute for handling bad routes.

 * Added a feature to flutter_driver that allows the host test script
   and the device test app to communicate.

 * Added a test to make sure `flutter drive --route` works.
   (Hopefully that will also prove `flutter run --route` works, though
   this isn't testing the `flutter` tool's side of that. My main
   concern is over whether the engine side works.)

 * Fixed `flutter drive` to output the right target file name.

 * Changed how the stocks app represents its data, so that we can
   show a page for a stock before we know if it exists.

 * Made it possible to show a stock page that doesn't exist. It shows
   a progress indicator if we're loading the data, or else shows a
   message saying it doesn't exist.

 * Changed the pathing structure of routes in stocks to work more
   sanely.

 * Made search in the stocks app actually work (before it only worked
   if we happened to accidentally trigger a rebuild). Added a test.

 * Replaced some custom code in the stocks app with a BackButton.

 * Added a "color" feature to BackButton to support the stocks use case.

 * Spaced out the ErrorWidget text a bit more.

 * Added `RouteSettings.copyWith`, which I ended up not using.

 * Improved the error messages around routing.

While I was in some files I made a few formatting fixes, fixed some
code health issues, and also removed `flaky: true` from some devicelab
tests that have been stable for a while. Also added some documentation
here and there.

I got a bit confused by these comments when trying to debug this code,
let's try clearing them up a little.

Fixes https://github.com/flutter/flutter/issues/10911

https://github.com/flutter/flutter/issues/10650

Fixes #10929

* Add hasAGoodToStringDeep and equalsIgnoringHashCodes methods.

Methods simplify testing of toStringDeep calls and other cases where
methods return strings containing hash codes.

This allows us to take advantage of improved command-line tooling (e.g.,
improvements in device listing in Instruments). Now that the engine is
built with Xcode 8 and the framework is tested against Xcode 8, this
reduces the set of configurations we need to support to allow us to
focus on the supported ones: Xcode 8 and Xcode 9.

...and make one of the comments accurate by fixing the code. Turns
out I forgot to add the 'silent' argument when I changed that comment.

This print statement provides no value to the user.

https://github.com/flutter/flutter/issues/10940

The upstream fix is: https://github.com/dart-lang/usage/commit/021664efd35d563ee21eadbed40af6b5e8e23b2e