JS: Exclude externs from CallGraph meta-query

Author: asgerf

javascript/ql/src/meta/alerts/CallGraph.ql

@@ -12,7 +12,10 @@ import javascript
 
 from DataFlow::Node invoke, Function f, string kind
 where
-  invoke.(DataFlow::InvokeNode).getACallee() = f and kind = "Call"
-  or
-  invoke.(DataFlow::PropRef).getAnAccessorCallee().getFunction() = f and kind = "Accessor call"
+  (
+    invoke.(DataFlow::InvokeNode).getACallee() = f and kind = "Call"
+    or
+    invoke.(DataFlow::PropRef).getAnAccessorCallee().getFunction() = f and kind = "Accessor call"
+  ) and
+  not f.getTopLevel().isExterns()
 select invoke, kind + " to $@", f, f.describe()