Clean the relayout subtree root deeply when removing a child, otherwise the tree ends up in an inco…

sky/sdk/lib/rendering/object.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:math' as math;
 import 'dart:sky' as sky;
 import 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
 
 import '../app/scheduler.dart' as scheduler;
 import '../framework/node.dart';
@@ skipping 47 matching lines @@
     setParentData(child);
     super.adoptChild(child);
     markNeedsLayout();
   }
   void dropChild(RenderObject child) { // only for use by subclasses
     assert(!debugDoingLayout);
     assert(!debugDoingPaint);
     assert(child != null);
     assert(child.parentData != null);
     child.parentData.detach();
-    if (child._relayoutSubtreeRoot != child) {
-      child._relayoutSubtreeRoot = null;
-      child._needsLayout = true;
-    }
+    child._cleanRelayoutSubtreeRoot();
     super.dropChild(child);
     markNeedsLayout();
   }
 
   static List<RenderObject> _nodesNeedingLayout = new List<RenderObject>();
   static bool _debugDoingLayout = false;
   static bool get debugDoingLayout => _debugDoingLayout;
   bool _needsLayout = true;
   bool get needsLayout => _needsLayout;
   RenderObject _relayoutSubtreeRoot;
@@ skipping 25 matching lines @@
     if (_relayoutSubtreeRoot != this) {
       final parent = this.parent; // TODO(ianh): Remove this once the analyzer is cleverer
       assert(parent is RenderObject);
       parent.markNeedsLayout();
       assert(parent == this.parent); // TODO(ianh): Remove this once the analyzer is cleverer
     } else {
       _nodesNeedingLayout.add(this);
       scheduler.ensureVisualUpdate();
     }
   }
+  void _cleanRelayoutSubtreeRoot() {
+    if (_relayoutSubtreeRoot != this) {
+      _relayoutSubtreeRoot = null;
+      _needsLayout = true;
+      _cleanRelayoutSubtreeRootChildren();
+    }
+  }
+  void _cleanRelayoutSubtreeRootChildren() { } // workaround for lack of inter-class mixins in Dart
   void scheduleInitialLayout() {
     assert(attached);
     assert(parent == null);
     assert(_relayoutSubtreeRoot == null);
     _relayoutSubtreeRoot = this;
     _nodesNeedingLayout.add(this);
     scheduler.ensureVisualUpdate();
   }
   static void flushLayout() {
     _debugDoingLayout = true;
@@ skipping 163 matching lines @@
       adoptChild(_child);
   }
   void attachChildren() {
     if (_child != null)
       _child.attach();
   }
   void detachChildren() {
     if (_child != null)
       _child.detach();
   }
+  void _cleanRelayoutSubtreeRootChildren() {
+    if (_child != null)
+      _child._cleanRelayoutSubtreeRoot();
+  }
   String debugDescribeChildren(String prefix) {
     if (child != null)
       return '${prefix}child: ${child.toString(prefix)}';
     return '';
   }
 }
 
 
 // GENERIC MIXIN FOR RENDER NODES WITH A LIST OF CHILDREN
 
@@ skipping 127 matching lines @@
     }
   }
   void detachChildren() {
     ChildType child = _firstChild;
     while (child != null) {
       child.detach();
       assert(child.parentData is ParentDataType);
       child = child.parentData.nextSibling;
     }
   }
+  void _cleanRelayoutSubtreeRootChildren() {
+    ChildType child = _firstChild;
+    while (child != null) {
+      child._cleanRelayoutSubtreeRoot();
+      assert(child.parentData is ParentDataType);
+      child = child.parentData.nextSibling;
+    }
+  }
 
   ChildType get firstChild => _firstChild;
   ChildType get lastChild => _lastChild;
   ChildType childAfter(ChildType child) {
     assert(child.parentData is ParentDataType);
     return child.parentData.nextSibling;
   }
 
   String debugDescribeChildren(String prefix) {
     String result = '';
     int count = 1;
     ChildType child = _firstChild;
     while (child != null) {
       result += '${prefix}child ${count}: ${child.toString(prefix)}';
       count += 1;
       child = child.parentData.nextSibling;
     }
     return result;
   }
 }