Do not eagerly add guarded leaf classes with CHA; do not add them for private names.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index db6dfaaf6b3be2e32ad41aedb19842689158e5f8..79df756c6880a5f1da0cf392aec0b16d77b00e49 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -3791,6 +3791,11 @@ bool Class::IsTopLevel() const {
 }
 
 
+bool Class::IsPrivate() const {
+  return Library::IsPrivate(String::Handle(Name()));
+}
+
+
 RawFunction* Class::LookupDynamicFunction(const String& name) const {
   return LookupFunction(name, kInstance);
 }