Rationalize Dart mojo and sky package structure

sky/framework/components/fixed_height_scrollable.dart

Index: sky/framework/components/fixed_height_scrollable.dart
diff --git a/sky/framework/components/fixed_height_scrollable.dart b/sky/framework/components/fixed_height_scrollable.dart
deleted file mode 100644
index e54ebafa2a9c4561a215b87ace49c33da2f55e68..0000000000000000000000000000000000000000
--- a/sky/framework/components/fixed_height_scrollable.dart
+++ /dev/null
@@ -1,106 +0,0 @@
-// 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 '../animation/scroll_behavior.dart';
-import '../debug/tracing.dart';
-import '../fn.dart';
-import 'dart:math' as math;
-import 'dart:async';
-import 'scrollable.dart';
-
-abstract class FixedHeightScrollable extends Scrollable {
-  static final Style _style = new Style('''
-    overflow: hidden;
-    position: relative;
-    will-change: transform;'''
-  );
-
-  static final Style _scrollAreaStyle = new Style('''
-    position:relative;
-    will-change: transform;'''
-  );
-
-  FixedHeightScrollable({
-    Object key
-  }) : super(key: key);
-
-  ScrollBehavior createScrollBehavior() => new OverscrollBehavior();
-  OverscrollBehavior get scrollBehavior => super.scrollBehavior as OverscrollBehavior;
-
-  double _height = 0.0;
-  double _itemHeight;
-
-  int _itemCount = 0;
-  int get itemCount => _itemCount;
-  void set itemCount (int value) {
-    if (_itemCount != value) {
-      _itemCount = value;
-      if (_itemHeight != null)
-        scrollBehavior.contentsHeight = _itemHeight * _itemCount;
-    }
-  }
-
-  void _measureHeights() {
-    trace('FixedHeightScrollable::_measureHeights', () {
-      if (_itemHeight != null)
-        return;
-      var root = getRoot();
-      if (root == null)
-        return;
-      var item = root.firstChild.firstChild;
-      if (item == null)
-        return;
-      setState(() {
-        _height = root.height;
-        assert(_height > 0);
-        _itemHeight = item.height;
-        assert(_itemHeight > 0);
-        scrollBehavior.containerHeight = _height;
-        scrollBehavior.contentsHeight = _itemHeight * _itemCount;
-      });
-    });
-  }
-
-  UINode buildContent() {
-    var itemNumber = 0;
-    var drawCount = 1;
-    var transformStyle = '';
-
-    if (_itemHeight == null)
-      new Future.microtask(_measureHeights);
-
-    if (_height > 0.0 && _itemHeight != null) {
-      if (scrollOffset < 0.0) {
-        double visibleHeight = _height + scrollOffset;
-        drawCount = (visibleHeight / _itemHeight).round() + 1;
-        transformStyle =
-          'transform: translateY(${(-scrollOffset).toStringAsFixed(2)}px)';
-      } else {
-        drawCount = (_height / _itemHeight).ceil() + 1;
-        double alignmentDelta = -scrollOffset % _itemHeight;
-        if (alignmentDelta != 0.0)
-          alignmentDelta -= _itemHeight;
-
-        double drawStart = scrollOffset + alignmentDelta;
-        itemNumber = math.max(0, (drawStart / _itemHeight).floor());
-
-        transformStyle =
-            'transform: translateY(${(alignmentDelta).toStringAsFixed(2)}px)';
-      }
-    }
-
-    return new Container(
-      style: _style,
-      children: [
-        new Container(
-          style: _scrollAreaStyle,
-          inlineStyle: transformStyle,
-          children: buildItems(itemNumber, drawCount)
-        )
-      ]
-    );
-  }
-
-  List<UINode> buildItems(int start, int count);  
-}