Dont call Platform.operatingSystem in RenderView diagnostics (#37637)

packages/flutter/lib/src/rendering/view.dart

@@ -256,7 +256,7 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
     // root superclasses don't include any interesting information for this
     // class
     assert(() {
-      properties.add(DiagnosticsNode.message('debug mode enabled - ${Platform.operatingSystem}'));
+      properties.add(DiagnosticsNode.message('debug mode enabled - ${kIsWeb ? 'Web' :  Platform.operatingSystem}'));
       return true;
     }());
     properties.add(DiagnosticsProperty<Size>('window size', _window.physicalSize, tooltip: 'in physical pixels'));