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 800fad3b3e2ee4b638f7fb5b8d450fa8a7986a86..2af97a61d7d10341a0fc423fffc2436a676dc0ca 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);
 }