Revert "Failure from a few days ago (returning null) on an exception masked error"

sdk/lib/html/html_common/conversions_dartium.dart

Index: sdk/lib/html/html_common/conversions_dartium.dart
diff --git a/sdk/lib/html/html_common/conversions_dartium.dart b/sdk/lib/html/html_common/conversions_dartium.dart
index 0f2c075177ae9ef82a144c13b023ad13b5ce5b4d..bdf8e9c17dfa7aa0ae02a71381af48610ac225b3 100644
--- a/sdk/lib/html/html_common/conversions_dartium.dart
+++ b/sdk/lib/html/html_common/conversions_dartium.dart
@@ -121,7 +121,7 @@ wrap_jso(jsObject) {
 
     var wrapper = js.getDartHtmlWrapperFor(jsObject);
     // if we have a wrapper return the Dart instance.
-    if (wrapper != null && wrapper is! js.JsObject) {
+    if (wrapper != null) {
       return wrapper;
     }