Replace some 'as' operators with equivalent code that doesn't do any checks in production mode.

sky/sdk/lib/framework/components2/ink_well.dart

Index: sky/sdk/lib/framework/components2/ink_well.dart
diff --git a/sky/sdk/lib/framework/components2/ink_well.dart b/sky/sdk/lib/framework/components2/ink_well.dart
index 5501ed76fca7d6d792a2eecc1ab46023e0ff407e..ca7399695c01c6fccb031029a0cbd56801a81da0 100644
--- a/sky/sdk/lib/framework/components2/ink_well.dart
+++ b/sky/sdk/lib/framework/components2/ink_well.dart
@@ -104,7 +104,7 @@ class InkWellWrapper extends OneChildRenderObjectWrapper {
   InkWellWrapper({ UINode child, Object key })
     : super(child: child, key: key);
 
-  RenderInkWell get root => super.root as RenderInkWell;
+  RenderInkWell get root { RenderInkWell result = super.root; return result; }
 
   RenderInkWell createNode() => new RenderInkWell();
 }