JavaScript: Add TaintKind as an alias to FlowLabel.

Author: Max Schaefer

javascript/ql/src/semmle/javascript/dataflow/Configuration.qll

@@ -220,6 +220,13 @@ abstract class FlowLabel extends string {
   bindingset[this] FlowLabel() { any() }
 }
 
+/**
+ * A kind of taint tracked by a taint-tracking configuration.
+ *
+ * This is an alias of `FlowLabel`, so the two types can be used interchangeably.
+ */
+class TaintKind = FlowLabel;
+
 /**
  * A standard flow label, that is, either `FlowLabel::data()` or `FlowLabel::taint()`.
  */