Fix bug 2907: cannot instantiate Dynamic.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 7391)
+++ runtime/vm/parser.cc	(working copy)
@@ -7672,6 +7672,9 @@
              "type parameter '%s' cannot be instantiated",
              String::Handle(type.Name()).ToCString());
   }
+  if (type.IsDynamicType()) {
+    ErrorMsg(type_pos, "Dynamic cannot be instantiated");
+  }
   Class& type_class = Class::Handle(type.type_class());
   String& type_class_name = String::Handle(type_class.Name());
   AbstractTypeArguments& type_arguments =