Refactor resolution code in the vm to properly handle ambiguity errors.

runtime/vm/compiler_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/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
 #include "vm/unit_test.h"
@@ skipping 24 matching lines @@
             "  }\n"
             "}\n";
   String& url = String::Handle(String::New("dart-test:CompileFunction"));
   String& source = String::Handle(String::New(kScriptChars));
   Script& script = Script::Handle(Script::New(url,
                                               source,
                                               RawScript::kScriptTag));
   Library& lib = Library::Handle(Library::CoreLibrary());
   EXPECT(CompilerTest::TestCompileScript(lib, script));
   EXPECT(ClassFinalizer::FinalizePendingClasses());
+  String& ambiguity_error_msg = String::Handle();
   Class& cls = Class::Handle(
-      lib.LookupClass(String::Handle(Symbols::New("A"))));
-  EXPECT(!cls.IsNull());
+      lib.LookupClass(String::Handle(Symbols::New("A")), &ambiguity_error_msg));
+  EXPECT(!cls.IsNull());  // No ambiguity error expected.
   String& function_foo_name = String::Handle(String::New("foo"));
   Function& function_foo =
       Function::Handle(cls.LookupStaticFunction(function_foo_name));
   EXPECT(!function_foo.IsNull());
 
   EXPECT(CompilerTest::TestCompileFunction(function_foo));
   EXPECT(function_foo.HasCode());
 
   String& function_moo_name = String::Handle(String::New("moo"));
   Function& function_moo =
       Function::Handle(cls.LookupStaticFunction(function_moo_name));
   EXPECT(!function_moo.IsNull());
 
   EXPECT(CompilerTest::TestCompileFunction(function_moo));
   EXPECT(function_moo.HasCode());
 }
 
 }  // namespace dart