Cleanup queryAll to return List<Element>.

lib/html/frog/html_frog.dart

Index: lib/html/frog/html_frog.dart
diff --git a/lib/html/frog/html_frog.dart b/lib/html/frog/html_frog.dart
index b19e02661d6818b4113a5940e9d8af43d8851466..73e8ee4beafd9d976c234071688894c22a22c066 100644
--- a/lib/html/frog/html_frog.dart
+++ b/lib/html/frog/html_frog.dart
@@ -4864,7 +4864,7 @@ class _DocumentImpl extends _NodeImpl implements Document
     return $dom_querySelector(selectors);
   }
 
-  ElementList queryAll(String selectors) {
+  List<Element> queryAll(String selectors) {
     if (const RegExp("""^\\[name=["'][^'"]+['"]\\]\$""").hasMatch(selectors)) {
       final mutableMatches = $dom_getElementsByName(
           selectors.substring(7,selectors.length - 2));
@@ -5138,7 +5138,7 @@ class _DocumentFragmentImpl extends _NodeImpl implements DocumentFragment native
 
   _ElementImpl query(String selectors) => $dom_querySelector(selectors);
 
-  ElementList queryAll(String selectors) =>
+  List<Element> queryAll(String selectors) =>
     new _FrozenElementList._wrap($dom_querySelectorAll(selectors));
 
   String get innerHTML() {
@@ -6062,7 +6062,7 @@ class _ElementImpl extends _NodeImpl implements Element native "*Element" {
 
   _ElementImpl query(String selectors) => $dom_querySelector(selectors);
 
-  ElementList queryAll(String selectors) =>
+  List<Element> queryAll(String selectors) =>
     new _FrozenElementList._wrap($dom_querySelectorAll(selectors));
 
   _CssClassSet get classes() => new _CssClassSet(this);
@@ -23042,7 +23042,11 @@ interface EXTTextureFilterAnisotropic {
 
 // WARNING: Do not edit - generated code.
 
-interface ElementList extends List<Element> {
+// TODO(vsm): Eliminate this type.
+
+// Note, ElementList implements List so that it's implementing classes
+// may be cast to List<? extends Element> - e.g., List<CanvasElement>.
+interface ElementList extends List {
   // TODO(jacobr): add element batch manipulation methods.
   ElementList filter(bool f(Element element));
 
@@ -23077,7 +23081,7 @@ interface ElementRect {
 
 interface NodeSelector {
   Element query(String selectors);
-  NodeList queryAll(String selectors);
+  List<Element> queryAll(String selectors);
 }
 
 /// @domName Element