add support for template repeat

lib/web_ui.dart

Index: lib/web_ui.dart
diff --git a/lib/web_ui.dart b/lib/web_ui.dart
index c899f2a93c9adb6c69075b83f9c5a55498e8afd5..d339b17121858f60cdd2491a3574f1ace86f0a94 100644
--- a/lib/web_ui.dart
+++ b/lib/web_ui.dart
@@ -26,6 +26,52 @@ import 'safe_html.dart' as safe_html;
 import 'templating.dart' as templating;
 import 'watcher.dart' as watcher;
 
+final Map _elements = new Map<String, _CustomElementInfo>();
+
+class _CustomElementInfo {
+  final Element _elementElement;
+  final DocumentFragment _template;
+  _CustomElementInfo(this._elementElement, this._template);
+}
+
+/**
+ * This API registers an `<element>` element with the runtime system, so script
+ * code can use [getElementDefinition] and [getElementTemplate].
+ *
+ * Note: normally you should not need to call this, it will be done
+ * automatically by web_ui as part of the polyfill for the
+ * [element HTML element](https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/custom/index.html#the-element-element).
+ */
+void registerElementDefinition(Element element, DocumentFragment template) {
+  var name = element.attributes['name'];
+  if (name == null) throw new ArgumentError('custom element must have a name.');
+  _elements[name] = new _CustomElementInfo(element, template);

[Siggi Cherem (dart-lang), 2013/04/05 20:09:24]

should we warn when there are conflicts on the name?

+}
+
+/**
+ * Gets the custom `<element>` corresponding to the given tag name.
+ * These are registered automatically, or explicitly by calling
+ * [registerElementDefinition].
+ *
+ * Note that the `<template>` node's contents are not accessible from the
+ * returned node, and should be accessed via [getElementTemplate].
+ */
+Element getElementDefinition(String tagName) =>
+    _elements[tagName]._elementElement;
+
+/**
+ * Gets the custom `<element>` template contents. Conceptually this is
+ * equivalent to:
+ *
+ *     getElementDefinition(tagName).template.content;
+ *
+ * However it works on browsers that don't have native support for
+ * `<element>` and `<template>`.
+ */
+DocumentFragment getElementTemplate(String tagName) =>
+    _elements[tagName]._template;
+
+

[Siggi Cherem (dart-lang), 2013/04/05 20:09:24]

looks like these changes below with a different change? (for the _root fix?)

[Jennifer Messerly, 2013/04/05 20:34:36]

Yes! good catch. :D

 /**
  * The base class for all Dart web components. In addition to the [Element]
  * interface, it also provides lifecycle methods: