Revert of [runtime] Introduce dedicated JSBoundFunction to represent bound functions.

src/api-natives.cc

Index: src/api-natives.cc
diff --git a/src/api-natives.cc b/src/api-natives.cc
index bc71e3ef90db8b9e9d3501d068fab670b66169df..2dd0fed0edd536ea77d989abc0d5e7d734a63dee 100644
--- a/src/api-natives.cc
+++ b/src/api-natives.cc
@@ -548,7 +548,7 @@
   // Mark instance as callable in the map.
   if (!obj->instance_call_handler()->IsUndefined()) {
     map->set_is_callable();
-    map->set_is_constructor();
+    map->set_is_constructor(true);
   }
 
   // Recursively copy parent instance templates' accessors,