Make the buttons on home.dart fill the screen width again

sky/home.dart

Index: sky/home.dart
diff --git a/sky/home.dart b/sky/home.dart
index 228042fe8315ec6898d15cd494350ba193c592c0..f566305722a0f5db988ac79a54c2e17869c3bcf5 100644
--- a/sky/home.dart
+++ b/sky/home.dart
@@ -38,9 +38,13 @@ class SkyDemo extends Component {
   }
 
   UINode build() {
-    return new RaisedButton(
-      child: new Text(text),
-      onPressed: _handlePress
+    return new ConstrainedBox(
+      // TOOD(ianh): Fix so we don't need INFINITY here.
+      constraints: new BoxConstraints.tightFor(width: double.INFINITY),
+      child: new RaisedButton(
+        child: new Text(text),
+        onPressed: _handlePress
+      )
     );
   }
 }