Use displayName in Error.stack rendering if present.

src/messages.cc

Index: src/messages.cc
diff --git a/src/messages.cc b/src/messages.cc
index 072ac1d5a694a41f7d33a21363cf114ee29ca05e..bb75364ddb83c25b1c198d4714036661b0fca09d 100644
--- a/src/messages.cc
+++ b/src/messages.cc
@@ -191,6 +191,14 @@ Handle<Object> CallSite::GetFunctionName() {
   return isolate_->factory()->null_value();
 }
 
+Handle<Object> CallSite::GetDebugName() {
+  Handle<Object> name = JSReceiver::GetDataProperty(
+      fun_, isolate_->factory()->display_name_string());
+  if (name->IsString() && String::cast(*name)->length() != 0) {
+    return Handle<String>::cast(name);
+  }
+  return isolate_->factory()->null_value();
+}
 
 Handle<Object> CallSite::GetScriptNameOrSourceUrl() {
   Handle<Object> script_obj(fun_->shared()->script(), isolate_);