It turns out that we aren't really using these. The identity logic is sufficient.

Also, add some asserts for a crash I had once but couldn't reproduce, in case that helps catch it next time.

Route (named routes) no longer have a key, and have their own storage for their names.
RouseState no longer has a key, and uses an owner field pointing to a StatefulComponent instead.
As such, RouteBase no longer has a key.

HistoryEntry no longer uses a global int to ensure uniqueness.

Propagated this to stocks app.

When we build widgets during layout we weren't notifying those widgets that
they were mounted. Now we notify mount status changes when exiting build phases
inside layout.

Fixes #176

Separate width and height parameters for Image widgets

Fix analyzer warnings

This change makes it easier to defined only the width or the height of an image
and let the other value be filled in from the image's intrinsic aspect ratio.

Fixes #175

Renamed AnimatedType to AnimatedValue

Updates sprite widget to handle changes to renderbox

Dismissable: animate "snap back", only call dismiss() once

Try to clarify initial execution.

This function took innerConstraints as an argument but used constraints internally.

Measurement tracking for fitness app.

There is an issue with the input control that prevents actually creating a measurement. Working on this with eseidel.

R=eseidel

Card Collection dismiss animation

Tweaks to launcher

Conflicts:
	sky/sdk/lib/rendering/flex.dart

Support for non-alphabetic baselines