Adds a SpriteWidget and simplifies sample game setup

Adds a SpriteWidget and simplifies sample game setup

R=abarth@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/96b8393884d9c1303b9dbfbe8a075655be66bc32

[viktorl, 2015-06-19 00:13:06]

viktorl@google.com changed reviewers:
+ abarth@chromium.org

[abarth-chromium, 2015-06-19 00:18:07]

https://codereview.chromium.org/1197493002/diff/1/sky/examples/game/lib/sprit...
File sky/examples/game/lib/sprite_widget.dart (right):

https://codereview.chromium.org/1197493002/diff/1/sky/examples/game/lib/sprit...
sky/examples/game/lib/sprite_widget.dart:8: SpriteWidget(NodeWithSize
this._rootNode, [SpriteBoxTransformMode this._transformMode =
SpriteBoxTransformMode.letterbox]);
You can remove the "NodeWithSize" annotation.  The compiler is smart enough to
get the type from the member variable declaration.

https://codereview.chromium.org/1197493002/diff/1/sky/examples/game/lib/sprit...
sky/examples/game/lib/sprite_widget.dart:10: SpriteBox get root { return
super.root; }
SpriteBox get root => super.root;

https://codereview.chromium.org/1197493002/diff/1/sky/examples/game/lib/sprit...
sky/examples/game/lib/sprite_widget.dart:14: NodeWithSize get rootNode =>
_rootNode;
You need to implement syncRenderObject.  Take a look at the other subclasses of
OneChildRenderObjectWrapper in basic.dart.

You might want to read
<https://github.com/domokit/mojo/blob/master/sky/sdk/lib/widgets/README.md#state>
if you haven't already.  syncRenderObject is the analog to syncFields for
RenderObjectWrappers.

[abarth-chromium, 2015-06-19 16:09:00]

lgtm

[viktorl, 2015-06-19 16:14:19]

Committed patchset #1 (id:1) manually as
96b8393884d9c1303b9dbfbe8a075655be66bc32 (presubmit successful).