Prohibit use of dynamic when extending or implementing classes (was crashing).

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 21216)
+++ runtime/vm/parser.cc	(working copy)
@@ -3071,14 +3071,19 @@
         ErrorMsg(member.name_pos, "factory name must be '%s'",
                  members->class_name().ToCString());
       }
+      // Do not bypass class resolution by using current_class() directly, since
+      // it may be a patch class.
       const Object& result_type_class = Object::Handle(
           UnresolvedClass::New(LibraryPrefix::Handle(),
                                *member.name,
                                member.name_pos));
-      // The type arguments of the result type are set during finalization.
-      member.type = &Type::ZoneHandle(Type::New(result_type_class,
-                                                TypeArguments::Handle(),
-                                                member.name_pos));
+      // The type arguments of the result type are the type parameters of the
+      // current class. Note that in the case of a patch class, they are copied
+      // from the class being patched.
+      member.type = &Type::ZoneHandle(Type::New(
+          result_type_class,
+          TypeArguments::Handle(current_class().type_parameters()),
+          member.name_pos));
     } else if (member.has_static) {
       ErrorMsg(member.name_pos, "constructor cannot be static");
     }
@@ -3301,6 +3306,11 @@
                class_name.ToCString(),
                String::Handle(super_type.UserVisibleName()).ToCString());
     }
+    if (super_type.IsDynamicType()) {
+      ErrorMsg(type_pos,
+               "class '%s' may not extend 'dynamic'",
+               class_name.ToCString());
+    }
     if (CurrentToken() == Token::kWITH) {
       super_type = ParseMixins(super_type);
     }
@@ -3842,6 +3852,9 @@
                "type parameter '%s' may not be used in interface list",
                String::Handle(interface.UserVisibleName()).ToCString());
     }
+    if (interface.IsDynamicType()) {
+      ErrorMsg(interface_pos, "'dynamic' may not be used in interface list");
+    }
     all_interfaces.Add(interface);
   } while (CurrentToken() == Token::kCOMMA);
   cls_interfaces = Array::MakeArray(all_interfaces);