Rationalize Dart mojo and sky package structure

sky/framework/components/floating_action_button.dart

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import '../fn.dart';
-import '../theme/colors.dart';
-import 'ink_well.dart';
-import 'material.dart';
-
-class FloatingActionButton extends Component {
-  // TODO(abarth): We need a better way to become a container for absolutely
-  // positioned elements.
-  static final Style _style = new Style('''
-    width: 56px;
-    height: 56px;
-    background-color: ${Red[500]};
-    border-radius: 28px;'''
-  );
-  static final Style _clipStyle = new Style('''
-    position: absolute;
-    justify-content: center;
-    align-items: center;
-    top: 0;
-    left: 0;
-    right: 0;
-    bottom: 0;
-    -webkit-clip-path: circle(28px at center);''');
-
-  UINode content;
-  int level;
-
-  FloatingActionButton({ Object key, this.content, this.level: 0 })
-      : super(key: key);
-
-  UINode build() {
-    List<UINode> children = [];
-
-    if (content != null)
-      children.add(content);
-
-    return new Material(
-      content: new Container(
-        style: _style,
-        children: [new StyleNode(new InkWell(children: children), _clipStyle)]),
-      level: level);
-  }
-}