Revert "Revert "Fix handling of cross-origin windows in dartium and better align general handling o…

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 ef02c00b649893a847584e2d827e179424b73e14..ce459206f534ab675f4553e037f31cdcc7ac82c6 100644
--- a/sdk/lib/html/html_common/conversions_dartium.dart
+++ b/sdk/lib/html/html_common/conversions_dartium.dart
@@ -267,9 +267,15 @@ Type lookupType(js.JsObject jsObject, bool isElement) {
       }
       prototype = js.JsNative.getProperty(prototype, '__proto__');
     }
-  } catch (e, stacktrace) {
-    if (e is DebugAssertException) print("${e.message}\n ${stacktrace}");
-    else print("${stacktrace}");
+  } catch (e) {
+    // This case can happen for cross frame objects.
+    if (js.JsNative.hasProperty(e, "postMessage")) {
+      // assume this is a Window. To match Dart2JS, separate conversion code
+      // in dart:html will switch the wrapper to a cross frame window as
+      // required.
+      // TODO(jacobr): we could consider removing this code completely.
+      return Window.instanceRuntimeType;
+    }
   }
   return js.JSObject.instanceRuntimeType;
 }