Fix crash in dart2js on type literal sends.

sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart

Index: sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart	(revision 30644)
+++ sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart	(working copy)
@@ -692,9 +692,7 @@
   }
 
   T visitTypeReferenceSend(Send node) {
-    // If [node] is not a type literal is the class name of a static access,
-    // in which case we don't use the type mask.
-    return elements.isTypeLiteral(node) ? types.typeType : null;
+    return elements.isTypeLiteral(node) ? types.typeType : types.dynamicType;
   }
 
   bool isThisOrSuper(Node node) => node.isThis() || node.isSuper();