Improve static type propagation.

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
@@ skipping 7992 matching lines @@
     if (!type_class.HasResolvedFactoryClass()) {
       // This error can occur only with bootstrap classes.
       const UnresolvedClass& unresolved =
           UnresolvedClass::Handle(type_class.UnresolvedFactoryClass());
       const String& missing_class_name = String::Handle(unresolved.ident());
       ErrorMsg("unresolved factory class '%s'", missing_class_name.ToCString());
     }
     // Only change the class of the constructor to the factory class if the
     // factory class implements the interface 'type'.
     const Class& factory_class = Class::Handle(type_class.FactoryClass());
-    Error& malformed_error = Error::Handle();
     if (factory_class.IsSubtypeOf(TypeArguments::Handle(),
                                   type_class,
                                   TypeArguments::Handle(),
-                                  &malformed_error)) {
+                                  NULL)) {
       // Class finalization verifies that the factory class has identical type
       // parameters as the interface.
       constructor_class_name = factory_class.Name();
     }
     // Always change the result type of the constructor to the factory type.
     constructor_class = factory_class.raw();
     // The finalized type_arguments are still those of the interface type.
     ASSERT(!constructor_class.is_interface());
   }
 
@@ skipping 677 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart