Make sure required type arguments are given when using factories.

sdk/lib/_internal/compiler/implementation/enqueue.dart

Index: sdk/lib/_internal/compiler/implementation/enqueue.dart
diff --git a/sdk/lib/_internal/compiler/implementation/enqueue.dart b/sdk/lib/_internal/compiler/implementation/enqueue.dart
index 125a355bc9e374777be6d0cc40cb69092374fcd2..c6ea16a7705f3b34c12e3e36cfe8da3d63eef08e 100644
--- a/sdk/lib/_internal/compiler/implementation/enqueue.dart
+++ b/sdk/lib/_internal/compiler/implementation/enqueue.dart
@@ -386,6 +386,15 @@ abstract class Enqueuer {
     compiler.backend.registerIsCheck(type, this, elements);
   }
 
+  /**
+   * If a factory constructor is used with type arguments, we lose track
+   * which arguments could be used to create instances of classes that use their
+   * type variables as expressions, so we have to remember if we saw such a use.
+   */
+  void registerFactoryWithTypeArguments(TreeElements elements) {
+    universe.usingFactoryWithTypeArguments = true;
+  }
+
   void registerAsCheck(DartType type, TreeElements elements) {
     registerIsCheck(type, elements);
     compiler.backend.registerAsCheck(type, elements);