Ref: https://developer.apple.com/xcode/

...and add --diagnostic-port.

...and document port 0.

...now that we have generic methods, their types need to be specified too.

- [x] Wire up dependency checker and plumb flags down to the right place

Fixes #7014

This ensures that accidental usages of dart:io's
file API don't creep in over time.

This removes direct file access from within flutter_tools
in favor of using `package:file` via a `FileSystem` that's
accessed via the `ApplicationContext`.

This lays the groundwork for us to be able to easily swap
out the underlying file system when running Flutter tools,
which will be used to provide a record/replay file system,
analogous to what we have for process invocations.

This argument will enable mocking of os-layer process invocations,
where the mock behavior will come from replaying a previously-
recorded set of invocations. At the point of process invocation,
the key metadata for the invocation will be looked up in the
recording's manifest, and iff a matching record exists in the
manifest, the process will be mocked out with data derived from
the corresponding recorded process (e.g. stdout, stderr, exit code).

This moves the various copies of port forwarding code in the Device subclasses into the ProtocolDiscovery class.

* move port forwarding to a common location
* throw exception if protocol Uri is not discovered or port forwarding fails
* cancel discovery protocol subscriptions on iOS launches (wasn't happening before)
* fix iOS port forwarding to match other implementations
* add tests

It is not enabled by default in the VM because applications not launched via the tools may try to connect with the debugger. This causes the debugger and the IDE to hang on Mac.

* reapply handle new Observatory URL changes
Fixes https://github.com/flutter/flutter/issues/6843

* allow non numeric IPv4 addresses
Fixes https://github.com/flutter/flutter/issues/7051

With this change, they're run via instance methods on an object
obtained through the context. This will allow us to substitute
that object in tests with replay/record versions to allow us to
mock out the os-layer in tests.

https://github.com/flutter/flutter/commit/737a55ef3e47036220e72f3b3e17353d461b5fab

#6972 

* Allow for application-specific log readers.

When running with prebuilt application binaries, those applications
aren't guaranteed to be named "Runner" (as it is when we build
the app locally in Flutter tools)

* convert pubGet to throw ToolExit on non-zero exit code
* convert commandValidator to throw ToolExit for non-zero exit code
* convert flutter commands to throw ToolExit for non-zero exit code
* use convenience method throwToolExit
* only show "if this problem persists" for unusual exceptions

* refactor device descriptions method - easier to add columns
* show device SDK version

Fixes #6311

Fixes #6283

* cleanup obtaining user home directory path
* refactor doctor and detect IntelliJ on Mac
* fix detect Flutter plugin for IntelliJ

When using --use-application-binary:

- [x] Stop flutter run from checking for a pubspec.yaml in current directory
- [x] Stop flutter run from invoking pub get
- [x] Set 'shouldBuild' based on --use-application-binary
- [x] Stop requiring 'lib/main.dart' to be present before running.
- [x] Stop building an FLX when launching on Android

cleanup https://github.com/flutter/flutter/issues/5789

This change adds a top-level getBuildDirectory func and funcs for
android, aot, asset, ios build products.

Developers may now add a "build-dir" mapping to their
~/.flutter_settings (JSON format) config file. Output directory is
relative to the main flutter application directory.

This change also changes the default build directory for iOS builds to a
subdirectory of the configured build directory, 'build/ios' by default.

- [x] Refactor view support into separate classes.
- [x] Make the hot runner grab the main view and call runFromSource on it.
- [x] Remove Device.needsDevFS (because it is always true).

* send ext.flutter.debugDumpApp; ext.flutter.reassemble

* expose debugDumpRenderTree

The new `empty_statements` lint (in the next DEV roll), flags these empty statements.  Harmless, except the one in `basic.dart` that fixes a real-life bug. :)

* send the reload source command for ios simulators

* review changes

* rewrite w/ a completer

* send supportsRestart flag when starting an app

* remove unused imports

* review comments

Fixes #4298

* show build progress; print app sizes

* add todo

* review comments

* remove unused import