lib/html/dart2js/html_dart2js.dart

Index: lib/html/dart2js/html_dart2js.dart
diff --git a/lib/html/dart2js/html_dart2js.dart b/lib/html/dart2js/html_dart2js.dart
index 5d8ead83c24466f9e463df0ada8f241ca25c5122..dcc8123d38211f738e7a2dad74b09bc63f1e5ce0 100644
--- a/lib/html/dart2js/html_dart2js.dart
+++ b/lib/html/dart2js/html_dart2js.dart
@@ -23,7 +23,7 @@ Document get document() native "return document;";
 _DocumentImpl get _document() native "return document;";
 
 Element query(String selector) => _document.query(selector);
-List<Element> queryAll(String selector) => _document.queryAll(selector);
+ElementList queryAll(String selector) => _document.queryAll(selector);
 
 // Workaround for tags like <cite> that lack their own Element subclass --
 // Dart issue 1990.
@@ -10420,11 +10420,11 @@ abstract class DocumentFragment extends Element {
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-class _FilteredElementList implements List {
+class FilteredElementList implements ElementList {
   final Node _node;
   final NodeList _childNodes;
 
-  _FilteredElementList(Node node): _childNodes = node.nodes, _node = node;
+  FilteredElementList(Node node): _childNodes = node.nodes, _node = node;
 
   // We can't memoize this, since it's possible that children will be messed
   // with externally to this class.
@@ -10433,6 +10433,16 @@ class _FilteredElementList implements List {
   List<Element> get _filtered =>
     new List.from(_childNodes.filter((n) => n is Element));
 
+  // Don't use _filtered.first so we can short-circuit once we find an element.
+  Element get first {
+    for (final node in _childNodes) {
+      if (node is Element) {
+        return node;
+      }
+    }
+    return null;
+  }
+
   void forEach(void f(Element element)) {
     _filtered.forEach(f);
   }
@@ -10543,11 +10553,11 @@ class _FrozenCSSClassSet extends _CssClassSet {
 }
 
 class _DocumentFragmentImpl extends _NodeImpl implements DocumentFragment native "*DocumentFragment" {
-  List<Element> _elements;
+  ElementList _elements;
 
-  List<Element> get elements {
+  ElementList get elements {
     if (_elements == null) {
-      _elements = new _FilteredElementList(this);
+      _elements = new FilteredElementList(this);
     }
     return _elements;
   }
@@ -10592,8 +10602,7 @@ class _DocumentFragmentImpl extends _NodeImpl implements DocumentFragment native
       case "beforebegin": return null;
       case "afterend": return null;
       case "afterbegin":
-        var first = this.nodes.length > 0 ? this.nodes[0] : null;
-        this.insertBefore(node, first);
+        this.insertBefore(node, this.nodes.first);
         return node;
       case "beforeend":
         this.nodes.add(node);
@@ -10642,12 +10651,7 @@ class _DocumentFragmentImpl extends _NodeImpl implements DocumentFragment native
   String get tagName => "";
   String get webkitdropzone => "";
   String get webkitRegionOverflow => "";
-  Element get $m_firstElementChild {
-    if (elements.length > 0) {
-      return elements[0];
-    }
-    return null;
-  }
+  Element get $m_firstElementChild() => elements.first();
   Element get $m_lastElementChild() => elements.last();
   Element get nextElementSibling => null;
   Element get previousElementSibling => null;
@@ -11145,6 +11149,21 @@ class _EXTTextureFilterAnisotropicImpl implements EXTTextureFilterAnisotropic na
 
 // WARNING: Do not edit - generated code.
 
+// TODO(vsm): Eliminate this type.
+
+// Note, ElementList implements List (instead of List<Element>) so
+// that its implementing classes may be cast to Lists of more specific
+// type such as List<CanvasElement>.
+abstract class ElementList implements List {
+  // TODO(jacobr): add element batch manipulation methods.
+  ElementList filter(bool f(Element element));
+
+  ElementList getRange(int start, int length);
+
+  Element get first;
+  // TODO(jacobr): add insertAt
+}
+
 /**
  * All your attribute manipulation needs in one place.
  * Extends the regular Map interface by automatically coercing non-string
@@ -11201,7 +11220,7 @@ abstract class Element implements Node, NodeSelector {
    * @domName childElementCount, firstElementChild, lastElementChild,
    *   children, Node.nodes.add
    */
-  List<Element> get elements;
+  ElementList get elements;
 
   void set elements(Collection<Element> value);
 
@@ -11550,7 +11569,7 @@ abstract class ElementEvents implements Events {
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
-class _ChildrenElementList implements List {
+class _ChildrenElementList implements ElementList {
   // Raw Element.
   final _ElementImpl _element;
   final _HTMLCollectionImpl _childElements;
@@ -11567,14 +11586,18 @@ class _ChildrenElementList implements List {
     return output;
   }
 
+  _ElementImpl get first {
+    return _element.$dom_firstElementChild;
+  }
+
   void forEach(void f(Element element)) {
     for (_ElementImpl element in _childElements) {
       f(element);
     }
   }
 
-  List<Element> filter(bool f(Element element)) {
-    final output = [];
+  ElementList filter(bool f(Element element)) {
+    final output = <Element>[];
     forEach((Element element) {
       if (f(element)) {
         output.add(element);
@@ -11696,7 +11719,7 @@ class _ChildrenElementList implements List {
 // a better option given that we cannot quite force NodeList to be an
 // ElementList as there are valid cases where a NodeList JavaScript object
 // contains Node objects that are not Elements.
-class _FrozenElementList implements List {
+class _FrozenElementList implements ElementList {
   final List<Node> _nodeList;
 
   _FrozenElementList._wrap(this._nodeList);
@@ -11719,8 +11742,8 @@ class _FrozenElementList implements List {
     return out;
   }
 
-  List<Element> filter(bool f(Element element)) {
-    final out = <Element>[];
+  ElementList filter(bool f(Element element)) {
+    final out = new _ElementList([]);
     for (Element el in this) {
       if (f(el)) out.add(el);
     }
@@ -11789,7 +11812,7 @@ class _FrozenElementList implements List {
     throw const UnsupportedOperationException('');
   }
 
-  List<Element> getRange(int start, int rangeLength) =>
+  ElementList getRange(int start, int rangeLength) =>
     new _FrozenElementList._wrap(_nodeList.getRange(start, rangeLength));
 
   int indexOf(Element element, [int start = 0]) =>
@@ -11833,6 +11856,16 @@ class _FrozenElementListIterator implements Iterator<Element> {
   bool hasNext() => _index < _list.length;
 }
 
+class _ElementList extends _ListWrapper<Element> implements ElementList {
+  _ElementList(List<Element> list) : super(list);
+
+  ElementList filter(bool f(Element element)) =>
+    new _ElementList(super.filter(f));
+
+  ElementList getRange(int start, int rangeLength) =>
+    new _ElementList(super.getRange(start, rangeLength));
+}
+
 class _ElementAttributeMap implements AttributeMap {
 
   final _ElementImpl _element;
@@ -12220,7 +12253,7 @@ class _ElementImpl extends _NodeImpl implements Element native "*Element" {
     elements.addAll(value);
   }
 
-  List<Element> get elements => new _ChildrenElementList._wrap(this);
+  ElementList get elements => new _ChildrenElementList._wrap(this);
 
   _ElementImpl query(String selectors) => $dom_querySelector(selectors);
 
@@ -12319,8 +12352,7 @@ class _ElementImpl extends _NodeImpl implements Element native "*Element" {
         this.parent.insertBefore(node, this);
         break;
       case 'afterbegin':
-        var first = this.nodes.length > 0 ? this.nodes[0] : null;
-        this.insertBefore(node, first);
+        this.insertBefore(node, this.nodes.first);
         break;
       case 'beforeend':
         this.nodes.add(node);
@@ -12502,7 +12534,7 @@ class _ElementFactoryProvider {
 
     Element element;
     if (temp.elements.length == 1) {
-      element = temp.elements[0];
+      element = temp.elements.first;
     } else if (parentTag == 'html' && temp.elements.length == 2) {
       // Work around for edge case in WebKit and possibly other browsers where
       // both body and head elements are created even though the inner html
@@ -21120,10 +21152,10 @@ class _ListWrapper<E> implements List<E> {
 class _NodeListWrapper extends _ListWrapper<Node> implements NodeList {
   _NodeListWrapper(List list) : super(list);
 
-  List<Node> filter(bool f(Node element)) =>
+  NodeList filter(bool f(Node element)) =>
     new _NodeListWrapper(_list.filter(f));
 
-  List<Node> getRange(int start, int rangeLength) =>
+  NodeList getRange(int start, int rangeLength) =>
     new _NodeListWrapper(_list.getRange(start, rangeLength));
 }
 
@@ -21154,7 +21186,7 @@ class _NodeListImpl implements NodeList, JavaScriptIndexingBehavior native "*Nod
 
   void addAll(Collection<_NodeImpl> collection) {
     for (_NodeImpl node in collection) {
-      _parent.$dom_appendChild(node);
+      _parent.$dom_appendChild(node);      
     }
   }
 
@@ -21212,7 +21244,7 @@ class _NodeListImpl implements NodeList, JavaScriptIndexingBehavior native "*Nod
   void insertRange(int start, int rangeLength, [Node initialValue]) {
     throw new UnsupportedOperationException("Cannot insertRange on immutable List.");
   }
-  List<Node> getRange(int start, int rangeLength) =>
+  NodeList getRange(int start, int rangeLength) =>
     new _NodeListWrapper(_Lists.getRange(this, start, rangeLength, <Node>[]));
 
   // -- end List<Node> mixins.
@@ -24842,7 +24874,7 @@ class _SVGElementImpl extends _ElementImpl implements SVGElement native "*SVGEle
     return _cssClassSet;
   }
 
-  List<Element> get elements => new _FilteredElementList(this);
+  ElementList get elements => new FilteredElementList(this);
 
   void set elements(Collection<Element> value) {
     final elements = this.elements;
@@ -24869,7 +24901,7 @@ class _SVGElementImpl extends _ElementImpl implements SVGElement native "*SVGEle
     // Wrap the SVG string in <svg> so that SVGElements are created, rather than
     // HTMLElements.
     container.innerHTML = '<svg version="1.1">$svg</svg>';
-    this.elements = container.elements[0].elements;
+    this.elements = container.elements.first.elements;
   }