Update handling of ambiguous name references

runtime/vm/cha_test.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 "platform/assert.h"
 #include "vm/cha.h"
 #include "vm/class_finalizer.h"
 #include "vm/globals.h"
 #include "vm/symbols.h"
 #include "vm/unit_test.h"
@@ skipping 15 matching lines @@
       "  foo() { }"
       "  bar() { }"
       "}\n";
 
   TestCase::LoadTestScript(kScriptChars, NULL);
   EXPECT(ClassFinalizer::FinalizePendingClasses());
   const String& name = String::Handle(String::New(TestCase::url()));
   const Library& lib = Library::Handle(Library::LookupLibrary(name));
   EXPECT(!lib.IsNull());
 
-  String& ambiguity_error_msg = String::Handle();
   const Class& class_a = Class::Handle(
-      lib.LookupClass(String::Handle(Symbols::New("A")), &ambiguity_error_msg));
+      lib.LookupClass(String::Handle(Symbols::New("A"))));
   EXPECT(!class_a.IsNull());
   const intptr_t class_a_id = class_a.id();
 
   const Class& class_b = Class::Handle(
-      lib.LookupClass(String::Handle(Symbols::New("B")), &ambiguity_error_msg));
+      lib.LookupClass(String::Handle(Symbols::New("B"))));
   EXPECT(!class_b.IsNull());
   const intptr_t class_b_id = class_b.id();
 
   const Class& class_c = Class::Handle(
-      lib.LookupClass(String::Handle(Symbols::New("C")), &ambiguity_error_msg));
+      lib.LookupClass(String::Handle(Symbols::New("C"))));
   EXPECT(!class_c.IsNull());
   const intptr_t class_c_id = class_c.id();
 
   const Class& class_d = Class::Handle(
-      lib.LookupClass(String::Handle(Symbols::New("D")), &ambiguity_error_msg));
+      lib.LookupClass(String::Handle(Symbols::New("D"))));
   EXPECT(!class_d.IsNull());
   const intptr_t class_d_id = class_d.id();
 
   const String& function_foo_name = String::Handle(String::New("foo"));
   const String& function_bar_name = String::Handle(String::New("bar"));
 
   const Function& class_a_foo =
       Function::Handle(class_a.LookupDynamicFunction(function_foo_name));
   EXPECT(!class_a_foo.IsNull());
 
@@ skipping 57 matching lines @@
   EXPECT(!CHA::HasSubclasses(kNullCid));
   EXPECT(!CHA::HasSubclasses(kDynamicCid));
   EXPECT(!CHA::HasSubclasses(kVoidCid));
   EXPECT(CHA::HasSubclasses(class_a_id));
   EXPECT(CHA::HasSubclasses(class_b_id));
   EXPECT(!CHA::HasSubclasses(class_c_id));
   EXPECT(!CHA::HasSubclasses(class_d_id));
 }
 
 }  // namespace dart