Fix background compilation issues when creating snapshots.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 9afe3fc37ceb3d49ad4d77fb5437a277ac0761c4..d19f1c32d3e64d6260b5ea8df2e6210dd5d8cf75 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -9435,10 +9435,10 @@ RawObject* Library::ResolveName(const String& name) const {
     // are not cached. This reduces the size of the the cache.
     return obj.raw();
   }
-  String& accessor_name = String::Handle(Field::GetterName(name));
+  String& accessor_name = String::Handle(Field::GetterSymbol(name));

[siva, 2016/04/04 22:45:38]

Is this really correct? It ends up adding this name to the symbol table.

Maybe you can do something similar to what is done in Namespace::Lookup and use
Field::LookupGetterSymbol that will not add anything to the symbol table.

[srdjan, 2016/04/04 23:22:49]

Done.

   obj = LookupLocalObject(accessor_name);
   if (obj.IsNull()) {
-    accessor_name = Field::SetterName(name);
+    accessor_name = Field::SetterSymbol(name);

[siva, 2016/04/04 22:45:38]

Ditto about adding the setter name to the symbol table.

[srdjan, 2016/04/04 23:22:49]

Done.

     obj = LookupLocalObject(accessor_name);
     if (obj.IsNull() && !ShouldBePrivate(name)) {
       obj = LookupImportedObject(name);