Replace LIBRARY_ELEMENT6 with LIBRARY_ELEMENT.

pkg/analyzer/test/src/task/dart_test.dart

Index: pkg/analyzer/test/src/task/dart_test.dart
diff --git a/pkg/analyzer/test/src/task/dart_test.dart b/pkg/analyzer/test/src/task/dart_test.dart
index 07e0e516fe116a84c56ca562a39a06fe68132be7..0aeee88a24af02722046ae823a5a97fd3508be4e 100644
--- a/pkg/analyzer/test/src/task/dart_test.dart
+++ b/pkg/analyzer/test/src/task/dart_test.dart
@@ -675,9 +675,9 @@ class C2 = C1 with M2;
 class C1 = B with M1;
 class C3 = B with M2;
 ''');
-    _computeResult(source, LIBRARY_ELEMENT6);
+    _computeResult(source, LIBRARY_ELEMENT);
     expect(task, new isInstanceOf<BuildLibraryConstructorsTask>());
-    LibraryElement libraryElement = outputs[LIBRARY_ELEMENT6];
+    LibraryElement libraryElement = outputs[LIBRARY_ELEMENT];
     // C1
     {
       ClassElement classElement = libraryElement.getType('C2');