Introduce LibraryEntity

pkg/compiler/lib/src/typechecker.dart

Index: pkg/compiler/lib/src/typechecker.dart
diff --git a/pkg/compiler/lib/src/typechecker.dart b/pkg/compiler/lib/src/typechecker.dart
index 0660e3dc1d19a294eb765e4b5a20496df8efd0aa..cb6557cf06b9aaa16b93c4c9cca1a81b266099b5 100644
--- a/pkg/compiler/lib/src/typechecker.dart
+++ b/pkg/compiler/lib/src/typechecker.dart
@@ -808,12 +808,13 @@ class TypeCheckerVisitor extends Visitor<ResolutionDartType> {
         void findPrivateMember(MemberSignature member) {
           if (memberName.isSimilarTo(member.name)) {
             PrivateName privateName = member.name;
+            LibraryElement library = privateName.library;
             reportMessage(
                 node,
                 MessageKind.PRIVATE_ACCESS,
                 {
                   'name': name,
-                  'libraryName': privateName.library.libraryOrScriptName
+                  'libraryName': library.libraryOrScriptName
                 },
                 isHint: isHint);
             foundPrivateMember = true;