This reverts commit d4d74d9c.

Address feedback from material design team.

Fixes #4144
Fixes #4145
Fixes #4146

For consistency.

Fixes #4142

Fixes #4114

When building AOT, we now run `pub get` instead of printing an error telling
the user to run `pub get`. We can remove this code once the bug reference above
is fixed (should be a couple days).

* iOS tools cleanup

1) Fix `flutter install` on both device and simulator to refer to the actual
   bundle and not just the .generated folder
2) Fix `flutter run` on device to actually run vs just installing

Still TODO:
1) Discovered that isAppInstalled on iOS simulator always reports true,
   meaning it'll never actually try to install the app.

Fixes #3947
Fixes #1823

The app.a wasn't getting pulled into the main executable because we weren't
referencing any of its symbols. Instead, create a dylib that can be packaged
with the application and loaded at runtime.

This patch teaches flutter build aot to build `app.a` for use with the Dart
interpreter.

Currently only android-arm and ios are supported target platforms.

On iOS, we use Xcode to build a static library that contains the precompiled
code. This code is currently unused, but it will be used by the new Xcode
harness to factor out as much complexity as possible into the flutter tool.

Our microbenchmarks now run on real devices.

Wire up ios-profile and ios-release. Switching between debug, profile and release starts the build process from scratch. (#4063)

We now match the spec much better, including handling dark theme.

The main thing we're still missing is the landscape layout.

Fixes #989

Fixes the breakage that https://github.com/flutter/flutter/pull/4092 would cause.

Small fixes to contributing documentation.

 - Using widgets/spinning_square.dart instead of non-existing
  examples/widgets for the `run -t` example
 - travis/test.sh -> dev/bots/test.sh
 - Couple of style changes.

For developers with the platform tools installed but no SDK, it prevents
crashing in the flutter tool in favor of more user-friendly error messages
downstream.