Add "matchingTarget" function to Event, which is the Element that matched the CSS value selector.

tools/dom/templates/html/impl/impl_Event.darttemplate

Index: tools/dom/templates/html/impl/impl_Event.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Event.darttemplate b/tools/dom/templates/html/impl/impl_Event.darttemplate
index a3fc47f660dd5faa429cd19a30bde06f4fc51673..5eb80eecfaf7e8dc7f5627ac55d689e0bb982f50 100644
--- a/tools/dom/templates/html/impl/impl_Event.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Event.darttemplate
@@ -34,6 +34,32 @@ $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
     return e;
   }
 
-  $CLASSNAME._private();

[blois, 2013/10/09 20:47:18]

Why remove of this?

[Emily Fortuna, 2013/10/09 22:16:28]

It got accidentally added in https://codereview.chromium.org/26279008/

+  /** 
+   * Caches the pointer to the element that matches CSS selector involved in
+   * the event.
+   */
+  Element _cachedMatchingTarget;
+
+  /**
+   * A pointer to the element whose CSS selector matched within which an event
+   * was fired. If this Event was not associated with any Event delegation,
+   * then this value will be null.
+   */
+  Element matchingTarget() {
+    if (_cachedMatchingTarget == null) {
+      var currentTarget = this.currentTarget;
+      var target = this.target;
+      var matchedTarget;
+      while (matchedTarget == null && target != currentTarget && 
+          target != null) {
+        if (target.matches('.selector')) {

[blois, 2013/10/09 20:47:18]

hardcoded??

[Emily Fortuna, 2013/10/09 22:16:28]

That's what I get for copying my comment from the bug discussion over here.
Fixed!

+          matchedTarget = target;
+        }
+        target = target.parent;
+      }
+      _cachedMatchingTarget = matchedTarget;
+    }
+    return _cachedMatchingTarget;
+  }
 $!MEMBERS
 }