Make 'where' lazy.

sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate

Index: sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate
diff --git a/sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate b/sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate
index 18f3e2df5813d986cb5b90a0f972dc83dfc05029..b5e28febb0b46228fb6e9e68c2bb60e3d5230c33 100644
--- a/sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate
+++ b/sdk/lib/html/templates/html/impl/impl_NodeList.darttemplate
@@ -19,7 +19,7 @@ class _ListWrapper<E> implements List<E> {
 
   Iterable mappedBy(f(E element)) => new MappedIterable<E, dynamic>(this, f);
 
-  List<E> where(bool f(E element)) => _list.where(f);
+  Iterable<E> where(bool f(E element)) => _list.where(f);
 
   bool every(bool f(E element)) => _list.every(f);
 
@@ -76,8 +76,7 @@ class _ListWrapper<E> implements List<E> {
 class _NodeListWrapper extends _ListWrapper<Node> implements List {
   _NodeListWrapper(List list) : super(list);
 
-  List<Node> where(bool f(Node element)) =>
-    new _NodeListWrapper(_list.where(f));
+  Iterable<Node> where(bool f(Node element)) => new WhereIterable(this, f);
 
   List<Node> getRange(int start, int rangeLength) =>
     new _NodeListWrapper(_list.getRange(start, rangeLength));
@@ -137,8 +136,7 @@ class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   Iterable mappedBy(f(Node element)) =>
       new MappedIterable<Node, dynamic>(this, f);
 
-  Collection<Node> where(bool f(Node element)) =>
-     new _NodeListWrapper(_Collections.where(this, <Node>[], f));
+  Iterable<Node> where(bool f(Node element)) => new WhereIterable(this, f);
 
   bool every(bool f(Node element)) => _Collections.every(this, f);