That way folks can customize it if they want (and it makes the code a
bit more self-documenting).

Now the label animates from its inline position to above the text and
the focus highlight grows into place.

RawEditableLine is now responsible for the scrolling behavior, which
removes the need for callbacks between RawEditableLine and Input. It
also fixes a bug whereby the whole Input widget (including its icon)
would scroll when the text got long.

Properly support labels, hints, icons, and custom typography.

Fixes #1308

This patch restructures how we size the editing region of the Input widget. Now
RenderEditableLine understands that it's a single-line editing widget and sizes
itself correctly.

Now you can colorize an Icon simply by proving a Color for the Icon.

When opening the keyboard or focusing an input widget, we should scroll the
widget into view so that the user can see what they're typing.

Instead, require the developer to opt-in to autofocusing because autofocusing
can be disruptive.

Fixes #1307

The space for the keyboard is now represented as bottom padding for the window.
By teaching the scaffold to respect the bottom window padding, we move the
floating action button and snackbars out of the way of the keyboard.

This currently works on Android. I'll need to see how to get the keyboard
geometry on iOS for a similar effect.

Fixes #103

Previously this code was in the animation layer, which didn't make much
sense because scrolling is a widget concern.

These should be the last references to the old "performance" name.

This patch removes Performance and AnimationValue now that we've ported the
framework over to AnimationController and Tween. This patch also cleans up the
names of the AnimationController classes now that they don't have to avoid
conflicts with the old animation API. Specifically, I've made the following
renames:

 * Animated -> Animation
 * Evaluatable -> Animatable
 * PerformanceStatus -> AnimationStatus

This patch is just renames and moving code around. There aren't any changes in
behavior.

I've left transitions and enter_exit_transition out of this patch, but I've
converted the rest.

After this patch, there aren't any direct uses of Performance in material.dart.

Providing a pre-built child is more efficient because we don't need to rebuild
the child every tick of the animation.

This patch moves Navigator and related code over to using
AnimationController.

Also, clean up the class hierarchy for AnimationController now that
we've renamed progress to value. That means everything in the hierarchy
now has a value, include Watchable. This patch renames Watchable to
Animated<T>, which lets us use that type almost everywhere.

I've added some ducktape to modal bottom sheets to avoid having to
refactor all of Navigator to use AnimationController. I'll remove the
ducktape in the next patch.

These now use Animation and AnimationController instead of PerformanceView and
Performance.

As part of this:
 - A lot of classes got new lerp functions, including e.g. TextStyle.
 - Theme's constructor story got overhauled. You can now configure
   everything if you really want to, and we're better about defaults.
 - Material no longer automatically animates its background color.
   (It still does for its shadow.)
 - Tabs try to get the indicator color from the theme.
 - The fields in ThemeData got reordered for sanity.
 - Theme.== and Theme.hashCode got fixed.
 - Typography got a bit of a spring cleaning.

Fixes #613.

The dart bindings changed semantics in a non-compatible way.

Introduces a new Tooltip class.
Adds support for tooltips to IconButton and Scaffold.
Adds some tooltips to various demos.

Also some tweaks to stack.dart that I made before I decided not to go
down a "CustomPositioned" route.

Some more asserts and toString info.
Reorder some code to group lerp-related functions.

The onHighlightChanged callback was being given "true" every time
instead of the actual value.

Previously we used a positional argument for widgets that had multiple
children. Now we use a named argument that defaults to an empty list.

Fixes #241

We use the ScrollDirection for more than just scrolling.

Fixes #151

- Add an option to enable debugPaintSizeEnabled.
- Add an option to enable the StatisticsOverlay.
- Add support for the StatisticsOverlay in MaterialApp.
- Change the layout behaviour of RenderStatisticsBox:
   - Give it a zero intrinsic width.
   - Give it an accurate intrinsic height that depends on the flags
     set. (Also, move the enum to the rendering/ layer from the
     widgets/ layer to enable this.)
   - Make the box automatically size itself full-width and the correct
     height, so that you can actually embed it (though most of the
     time you'd just put it in a Stack so this doesn't matter as
     much, really).
- Some style nit fixes in statistics_box.dart.

When the TabView widget's children change, we don't change the children
we give to the PageViewport because we fail to update _items. This patch
watches didChangeConfig and updates _items appropriately.

Fixes #1134
Fixes #1168

Instead of taking a builder and a generic type, we can just take a
List<Widget>.

This makes it more consistent with tightFor(), and also makes it
easier to tighten both directions at once when you're not sure you
will always do so (e.g. if you have a height and width that might be
null, and want to tighten whichever ones aren't null).

When I tightened up the layout constraints for the Drawer in the
Scaffold, I ended up making the edge swipe detector cover the entire
screen.  This patch fixes that issue by putting the gesture detector for
the edge swipe just around the container with the proper width. We now
use a global key to maintain the state across hierarchy changes.