Add Element.endSourceSpan

lib/dom.dart

 /// A simple tree API that results from parsing html. Intended to be compatible
 /// with dart:html, but it is missing many types and APIs.
 library dom;
 
 // TODO(jmesserly): lots to do here. Originally I wanted to generate this using
 // our Blink IDL generator, but another idea is to directly use the excellent
 // http://dom.spec.whatwg.org/ and http://html.spec.whatwg.org/ and just
 // implement that.
 
 import 'dart:collection';
@@ skipping 424 matching lines @@
 }
 
 // TODO(jmesserly): Elements should have a pointer back to their document
 class Element extends Node with _ParentNode, _ElementAndDocument {
   final String namespaceUri;
 
   /// The [local name](http://dom.spec.whatwg.org/#concept-element-local-name)
   /// of this element.
   final String localName;
 
+  // TODO(jmesserly): consider using an Expando for this, and put it in
+  // dom_parsing. Need to check the performance affect.
+  /// The source span of the end tag this element, if it was created by the
+  /// [HtmlParser]. May be `null` if does not have an implicit end tag.
+  FileSpan endSourceSpan;
+
   Element._(this.localName, [this.namespaceUri]) : super._();
 
   Element.tag(this.localName)
       : namespaceUri = Namespaces.html,
         super._();
 
   static final _START_TAG_REGEXP = new RegExp('<(\\w+)');
 
   static final _CUSTOM_PARENT_TAG_MAP = const {
     'body': 'html',
@@ skipping 534 matching lines @@
 
 class _ConcatTextVisitor extends TreeVisitor {
   final _str = new StringBuffer();
 
   String toString() => _str.toString();
 
   visitText(Text node) {
     _str.write(node.data);
   }
 }