Set 'enclosingElement' for FunctionElementImpl_forLUB.

pkg/analyzer/test/src/summary/resynthesize_common.dart

Index: pkg/analyzer/test/src/summary/resynthesize_common.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_common.dart b/pkg/analyzer/test/src/summary/resynthesize_common.dart
index e45e9bab08100793b5f26da86a3b4f2ad115572a..879fbe8297d9943b931bb94206001cb5d83c9027 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@@ -9609,6 +9609,9 @@ class B extends A {
   }
 
   void test_inferredType_usesSyntheticFunctionType_functionTypedParam() {
+    // AnalysisContext does not set the enclosing element for the synthetic
+    // FunctionElement created for the [f, g] type argument.
+    shouldCompareLibraryElements = false;
     var library = checkLibrary('''
 int f(int x(String y)) => null;
 String g(int x(String y)) => null;