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

runtime/vm/snapshot.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/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
@@ skipping 194 matching lines @@
          !IsSingletonClassId(GetVMIsolateObjectId(class_header)));
   ASSERT((SerializedHeaderTag::decode(class_header) != kObjectId) ||
          !IsObjectStoreClassId(SerializedHeaderData::decode(class_header)));
   Class& cls = Class::ZoneHandle(isolate(), Class::null());
   AddBackRef(object_id, &cls, kIsDeserialized);
   // Read the library/class information and lookup the class.
   str_ ^= ReadObjectImpl(class_header);
   library_ = Library::LookupLibrary(str_);
   ASSERT(!library_.IsNull());
   str_ ^= ReadObjectImpl();
-  cls = library_.LookupClass(str_);
+  cls = library_.LookupClass(str_, NULL);  // No ambiguity error expected.
   cls.EnsureIsFinalized(isolate());
   ASSERT(!cls.IsNull());
   return cls.raw();
 }
 
 
 RawObject* SnapshotReader::ReadObjectImpl() {
   int64_t value = Read<int64_t>();
   if ((value & kSmiTagMask) == kSmiTag) {
     return NewInteger(value);
@@ skipping 1247 matching lines @@
     UnmarkAll();
     isolate->set_long_jump_base(base);
   } else {
     isolate->set_long_jump_base(base);
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart