merge class extensions from patch files

test/generated_sdk/lib/core/function.dart

Index: test/generated_sdk/lib/core/function.dart
diff --git a/test/generated_sdk/lib/core/function.dart b/test/generated_sdk/lib/core/function.dart
index 9146397aeae04ac22b4514f36d1e2ab23d8edad0..f1f73bd0a5e89d573eb56903b85ee42dca8c23d3 100644
--- a/test/generated_sdk/lib/core/function.dart
+++ b/test/generated_sdk/lib/core/function.dart
@@ -68,4 +68,13 @@ abstract class Function {
    * own `operator==` and `hashCode` depending on the object.
    */
   bool operator==(Object other);
+
+  static Map<String, dynamic> _toMangledNames(
+      Map<Symbol, dynamic> namedArguments) {
+    Map<String, dynamic> result = {};
+    namedArguments.forEach((symbol, value) {
+      result[_symbolToString(symbol)] = value;
+    });
+    return result;
+  }
 }