Move matches method so that it gets generated for dart2js and dartium.

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

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 99a9b37226cec0281f8bce4c688e28ff0202c5b4..af46c5860d9d50f81d01145e7ea88c9d41da4c5b 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -872,6 +872,7 @@ $if DART2JS
         throw new ArgumentError("Invalid position ${where}");
     }
   }
+$endif
 
   /**
    * Checks if this element matches the CSS selectors.
@@ -889,8 +890,6 @@ $if DART2JS
     }
     throw new UnsupportedError("Not supported on this platform");
   }
-$else
-$endif
 
 $if DART2JS
   @Creates('Null')  // Set from Dart code; does not instantiate a native type.