Remove unnecessary JSObject implementation in memory web interop type

Author: rishika0212

packages/devtools_app/lib/src/framework/observer/_memory_web.dart

@@ -65,8 +65,7 @@ extension type _UserAgentSpecificMemoryBreakdownAttributionElement._(JSObject _)
 @JS()
 extension type _UserAgentSpecificMemoryBreakdownAttributionContainerElement._(
   JSObject _
-)
-    implements JSObject {
+) {
   external String get id;
 
   external String get url;