Improve stocks2 performance

sky/sdk/lib/rendering/paragraph.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 'dart:sky' as sky;
 
 import 'box.dart';
 import 'object.dart';
 import '../painting/text_style.dart';
 
 abstract class InlineBase {
   sky.Node _toDOM(sky.Document owner);
   String toString([String prefix = '']);
 }
 
 class InlineText extends InlineBase {
   InlineText(this.text) {
     assert(text != null);
   }
 
   final String text;
 
   sky.Node _toDOM(sky.Document owner) {
     return owner.createText(text);
   }
 
+  bool operator ==(other) => other is InlineText && text == other.text;
+  int get hashCode => text.hashCode;
+
   String toString([String prefix = '']) => '${prefix}InlineText: "${text}"';
 }
 
 class InlineStyle extends InlineBase {
   InlineStyle(this.style, this.children) {
     assert(style != null);
     assert(children != null);
   }
 
   final TextStyle style;
   final List<InlineBase> children;
 
   sky.Node _toDOM(sky.Document owner) {
     sky.Element parent = owner.createElement('t');
     style.applyToCSSStyle(parent.style);
     for (InlineBase child in children) {
       parent.appendChild(child._toDOM(owner));
     }
     return parent;
   }
 
+  bool operator ==(other) {
+    if (identical(this, other))
+      return true;
+    if (other is! InlineStyle
+        || style != other.style
+        || children.length != other.children.length)
+      return false;
+    for (int i = 0; i < children.length; ++i) {
+      if (children[i] != other.children[i])
+        return false;
+    }
+    return true;
+  }
+
+  int get hashCode {
+    int value = 373;
+    value = 37 * value + style.hashCode;
+    for (InlineBase child in children)
+      value = 37 * value + child.hashCode;
+    return value;
+  }
+
   String toString([String prefix = '']) {
     List<String> result = [];
     result.add('${prefix}InlineStyle:');
     var indent = '${prefix}  ';
     result.add('${style.toString(indent)}');
     for (InlineBase child in children) {
       result.add(child.toString(indent));
     }
     return result.join('\n');
   }
@@ skipping 18 matching lines @@
   }
 
   final sky.Document _document = new sky.Document();
   final sky.LayoutRoot _layoutRoot = new sky.LayoutRoot();
 
   InlineBase _inline;
   BoxConstraints _constraintsForCurrentLayout;
 
   InlineBase get inline => _inline;
   void set inline (InlineBase value) {
+    if (_inline == value)
+      return;
     _inline = value;
     _layoutRoot.rootElement.setChild(_inline._toDOM(_document));
     markNeedsLayout();
   }
 
   void _layout(BoxConstraints constraints) {
     _layoutRoot.maxWidth = constraints.maxWidth;
     _layoutRoot.minWidth = constraints.minWidth;
     _layoutRoot.minHeight = constraints.minHeight;
     _layoutRoot.maxHeight = constraints.maxHeight;
@@ skipping 50 matching lines @@
   }
 
   // we should probably expose a way to do precise (inter-glpyh) hit testing
 
   String debugDescribeSettings(String prefix) {
     String result = '${super.debugDescribeSettings(prefix)}';
     result += '${prefix}inline: ${inline}\n';
     return result;
   }
 }