* Document flutter run --machine at the bottom of the doc
* Be consistent with prefixes

Fixes https://github.com/flutter/flutter/issues/14517
Or at least, fixes the crash part of that.

* Documented nested navigators in the Navigator class file (#15040).

This reverts commit 4f1b6604.

Now that we have thousands of tests, it doesn't make sense to display a separate line for each test. The result is just megabytes of logs that you have to scrub through to find error messages.

Fixes #15198.

* TextFormField/TextField - remove spaces in character counter(follow material design guidelines)

The change in 8b8d368d has only renamed the flag in a subset of the
places.

We were already skipping the check in `flutter upgrade` but this also spawns `flutter precache` and `flutter doctor` which would still check and potentially output the message.

Eliminates 64-bit hardcoding for iOS test apps under dev/. This brings
them in line with the default iOS app templates.

Also, fixes "flutter run" for golden tests, and some docs.

* Eliminate arm64 restriction in iOS framework plist (flutter/engine#5435)
* Roll src/third_party/skia 458f40a..e70c5fb (4 commits) (flutter/engine#5433)
* Call SkAutoCanvasRestore with doSave = true (flutter/engine#5432)

flutter/engine@15ddcd4 Roll src/third_party/skia e45752e..0390d3e (8 commits)
flutter/engine@89eb6a3 call existing ostream operator for SkMatrix
flutter/engine@8360553 Roll src/third_party/skia 588f879..e45752e (24 commits)
flutter/engine@6bfd413 Synchronizes analysis_options.yaml files, and turns on Function typedef lint.

This reverts commit 59bb2dba.