Fix background compilation issues when creating snapshots.

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 9417 matching lines @@
   Object& obj = Object::Handle();
   if (FLAG_use_lib_cache && LookupResolvedNamesCache(name, &obj)) {
     return obj.raw();
   }
   obj = LookupLocalObject(name);
   if (!obj.IsNull()) {
     // Names that are in this library's dictionary and are unmangled
     // are not cached. This reduces the size of the the cache.
     return obj.raw();
   }
-  String& accessor_name = String::Handle(Field::GetterName(name));
-  obj = LookupLocalObject(accessor_name);
+  String& accessor_name = String::Handle(Field::LookupGetterSymbol(name));
+  if (!accessor_name.IsNull()) {
+    obj = LookupLocalObject(accessor_name);
+  }
   if (obj.IsNull()) {
-    accessor_name = Field::SetterName(name);
-    obj = LookupLocalObject(accessor_name);
+    accessor_name = Field::LookupSetterSymbol(name);
+    if (!accessor_name.IsNull()) {
+      obj = LookupLocalObject(accessor_name);
+    }
     if (obj.IsNull() && !ShouldBePrivate(name)) {
       obj = LookupImportedObject(name);
     }
   }
   AddToResolvedNamesCache(name, obj);
   return obj.raw();
 }
 
 
 class StringEqualsTraits {
@@ skipping 12404 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart