Make function-ref only show a link for Dart functions

runtime/observatory/lib/src/elements/function_ref.dart

Index: runtime/observatory/lib/src/elements/function_ref.dart
diff --git a/runtime/observatory/lib/src/elements/function_ref.dart b/runtime/observatory/lib/src/elements/function_ref.dart
index 1f4d06f5dfd99ba861e658814228682b9721ebf6..d91a512bb9bcc3cc70b221e00a7a64348fd5dbaa 100644
--- a/runtime/observatory/lib/src/elements/function_ref.dart
+++ b/runtime/observatory/lib/src/elements/function_ref.dart
@@ -26,6 +26,10 @@ class FunctionRefElement extends ServiceRefElement {
     if (ref == null) {
       return;
     }
+    if (!function.kind.isDart()) {
+      insertTextSpanIntoShadowRoot(name);
+      return;
+    }
     if (qualified) {
       if (function.dartOwner is ServiceFunction) {
         var functionRef = new Element.tag('function-ref');