Now that there's a new string_scanner in town, we're having dependency
resolution conflict because of flutter_markdown's tight dependency. This
patch loosens the dependency and resolves the conflict.

BUG=https://github.com/flutter/flutter/issues/4321
BUG=https://github.com/flutter/flutter/issues/4349

This patch exposes a convenience function on Scrollable that helps with
updating the scroll extents and ports several clients over to using it.

Assigning to `size` called our intrinsic sizing functions re-entrantly, which
is a destructive operation on TextPainter. Ideally we'd made that a
non-destructive operation, but in the meantime we can fix the tab fading issue
by grabbing the text size before assigning to `size`.

Fixes #4365

The `flutter.buildMode` property now controls whether to build in debug,
profiling, or release.

Fix flutter analyze defaults when files are specified (#4091).

Also, add more dartdoc to widgets.dart.

Turns out we have the same demo in the "Buttons" section now.
We don't need both.

This patch sets a default path for Flutter.framework that's sensible based on
the FLUTTER_MODE.

The hello_services example can now be built both for Android and iOS.

* Pesto demo for the Flutter Gallery app.

* pesto.special.case

Add a FLUTTER_MODE variable to the generated Xcconfig and fix snapshot generation on all targets. (#4362)

Get rid of the DART_EXPERIMENTAL_INTERPRETER_FLAG.

This patch adds some sensible defaults to xcode_backend.sh and documents how to
build hello_services for iOS using Xcode.

I changed the behavior late in the code review but didn't update this dartdoc.

Disables current package and current directory analysis when files are specified.

Fixes: https://github.com/flutter/flutter/issues/4091.

Update Dart SDK to 1.17.0-dev.6.2.

Latest RC.

Fixes two release blockers (https://github.com/dart-lang/sdk/issues/26558 and https://github.com/dart-lang/sdk/issues/26596); bonus points for letting us re-enable the `iterable_contains_unrelated_type` lint :).

This patch starts working through the missing dartdocs in widgets.dart.

Previously we supplied individual parameters to the various drag and pan
callbacks. However, that approach isn't extensible because each new
parameter is a breaking change to the API.

This patch makes a one-time breaking change to the API to provide a
"details" object that we can extend over time as we need to expose more
information. The first planned extension is adding enough information to
accurately produce an overscroll glow on Android.

The old code had gotten crufty with all the refactors. This simplifies
it down to what it really means.

Also, add a bunch of tests.

We used to rely on BoxConstraints.deflate's clamping, but now we have to
roll our own.

Don't send usage information on Chrome infra bots

We now describe what each parameter does.

Fixes #4256

All of the public APIs in rendering.dart now have dartdocs.

This required refactoring some cases where we weren't following the rules for
the protected annotation.

Although beautiful, having a continuous animation on the front page of the
gallery gives the impression that Flutter burns battery and makes phones hot.
This patch replaces the animation with solid purple. However, we might
eventually want to use a static image.

This demo burns battery continuously even when there's no change to the visual
appearance. This patch removes this demo to avoid giving the impression that
Flutter burns battery.

Related to #4120