Better type for _match argument in AttributeMatch

tools/dom/src/AttributeMap.dart

Index: tools/dom/src/AttributeMap.dart
diff --git a/tools/dom/src/AttributeMap.dart b/tools/dom/src/AttributeMap.dart
index 49f97eac67c7dfaf33e515a0296f5a702cb1c6b7..15a5ee156ab4ff9e817c1e13a60c4b73fe65a1c9 100644
--- a/tools/dom/src/AttributeMap.dart
+++ b/tools/dom/src/AttributeMap.dart
@@ -85,7 +85,7 @@ abstract class _AttributeMap implements Map<String, String> {
   /**
    * Checks to see if the node should be included in this map.
    */
-  bool _matches(Node node);
+  bool _matches(_Attr node);
 }
 
 /**
@@ -119,7 +119,7 @@ class _ElementAttributeMap extends _AttributeMap {
     return keys.length;
   }
 
-  bool _matches(Node node) => node._namespaceUri == null;
+  bool _matches(_Attr node) => node._namespaceUri == null;
 }
 
 /**
@@ -155,7 +155,7 @@ class _NamespacedAttributeMap extends _AttributeMap {
     return keys.length;
   }
 
-  bool _matches(Node node) => node._namespaceUri == _namespace;
+  bool _matches(_Attr node) => node._namespaceUri == _namespace;
 }
 
 /**