Fix summary resynthesis in the event of a self-import.

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

Index: pkg/analyzer/test/src/summary/resynthesize_ast_test.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_ast_test.dart b/pkg/analyzer/test/src/summary/resynthesize_ast_test.dart
index 29848a742db6e26a96a9d78f8edc82599c894b72..9d7a10d109f0a592a38a2d6763554030634e9284 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_ast_test.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_ast_test.dart
@@ -617,12 +617,13 @@ class ResynthesizeAstTest extends ResynthesizeTest
   bool get checkPropagatedTypes => false;
 
   @override
-  void checkLibrary(String text,
+  LibraryElementImpl checkLibrary(String text,
       {bool allowErrors: false, bool dumpSummaries: false}) {
     Source source = addTestSource(text);
     LibraryElementImpl resynthesized = _encodeDecodeLibraryElement(source);
     LibraryElementImpl original = context.computeLibraryElement(source);
     checkLibraryElements(original, resynthesized);
+    return resynthesized;
   }
 
   @override