Allow matchingTarget to also include the currentTarget.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 23314254c91e9493b31d81e6e151ddc8a9f8d174..548fd38e5ba85c696a1a0e6cabfefd36a3969dd6 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -10716,13 +10716,11 @@ class Event extends Interceptor native "Event" {
     var currentTarget = this.currentTarget;
     var target = this.target;
     var matchedTarget;
-    while (matchedTarget == null && target != currentTarget && target != null) {
-      if (target.matches(_selector)) {
-        matchedTarget = target;
-      }
+    do {
+      if (target.matches(_selector)) return target;
       target = target.parent;
-    }
-    return matchedTarget;
+    } while (target != null && target != currentTarget.parent);
+    throw new StateError('No selector matched for populating matchedTarget.');
   }
   // To suppress missing implicit constructor warnings.
   factory Event._() { throw new UnsupportedError("Not supported"); }