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

runtime/vm/code_descriptors_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/globals.h"
 
 #include "vm/ast.h"
 #include "vm/assembler.h"
 #include "vm/code_descriptors.h"
@@ skipping 207 matching lines @@
       "    var i = A.foo();"
       "    Expect.equals(30, i);"
       "  }\n"
       "}\n";
   // First setup the script and compile the script.
   TestCase::LoadTestScript(kScriptChars, native_resolver);
   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();
   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.
 
   // Now compile the two functions 'A.foo' and 'A.moo'
   String& function_moo_name = String::Handle(String::New("moo"));
   Function& function_moo =
       Function::Handle(cls.LookupStaticFunction(function_moo_name));
   EXPECT(CompilerTest::TestCompileFunction(function_moo));
   EXPECT(function_moo.HasCode());
 
   String& function_foo_name = String::Handle(String::New("foo"));
   Function& function_foo =
@@ skipping 35 matching lines @@
   // Now invoke 'A.moo' and it will trigger a GC when the native function
   // is called, this should then cause the stack map of function 'A.foo'
   // to be traversed and the appropriate objects visited.
   const Object& result = Object::Handle(
       DartEntry::InvokeFunction(function_foo, Object::empty_array()));
   EXPECT(!result.IsError());
 }
 
 }  // namespace dart