fix test

Author: mdebbar

lib/web_ui/lib/src/engine/window.dart

@@ -801,7 +801,7 @@ class EngineWindow extends ui.Window {
   }
 
   void _addUrlStrategyListener() {
-    _onUrlStrategy = setUrlStrategy;
+    _onUrlStrategy = allowInterop(setUrlStrategy);
     registerHotRestartListener(() {
       _onUrlStrategy = null;
     });

lib/web_ui/test/engine/history_test.dart

@@ -555,4 +555,7 @@ class TestPlatformLocation extends PlatformLocation {
   void go(int count) {
     throw UnimplementedError();
   }
+
+  @override
+  String getBaseHref() => '/';
 }