Introduce DartType.unaliased to avoid use of Resolution in the backend.

pkg/compiler/lib/src/dump_info.dart

Index: pkg/compiler/lib/src/dump_info.dart
diff --git a/pkg/compiler/lib/src/dump_info.dart b/pkg/compiler/lib/src/dump_info.dart
index e9d7c05434a32c471e95384baa00dee16c419c52..85699e575e068945cc093c4c7bc9338ac6fd298b 100644
--- a/pkg/compiler/lib/src/dump_info.dart
+++ b/pkg/compiler/lib/src/dump_info.dart
@@ -115,7 +115,7 @@ class ElementInfoCollector extends BaseElementVisitor<Info, dynamic> {
   }
 
   TypedefInfo visitTypedefElement(TypedefElement element, _) {
-    if (element.alias == null) return null;
+    if (!element.isResolved) return null;
     TypedefInfo info = new TypedefInfo(element.name, '${element.alias}',
         _unitInfoForElement(element));
     _elementToInfo[element] = info;