JS: let RegExpLiteral be a DataFlow::SourceNode

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

@@ -211,6 +211,7 @@ module SourceNode {
    *   - object expressions
    *   - array expressions
    *   - JSX literals
+   *   - regular expression literals
    *
    * This class is for internal use only and should not normally be used directly.
    */
@@ -224,7 +225,8 @@ module SourceNode {
         astNode instanceof ArrayExpr or
         astNode instanceof JSXNode or
         astNode instanceof GlobalVarAccess or
-        astNode instanceof ExternalModuleReference
+        astNode instanceof ExternalModuleReference or
+        astNode instanceof RegExpLiteral
       )
       or
       exists(SsaExplicitDefinition ssa, VarDef def |

javascript/ql/test/library-tests/DataFlow/sources.expected

@@ -11,6 +11,7 @@
 | sources.js:3:2:3:1 | this |
 | sources.js:3:2:5:1 | functio ... x+19;\\n} |
 | sources.js:3:11:3:11 | x |
+| sources.js:7:1:7:3 | /x/ |
 | tst.js:1:1:1:0 | this |
 | tst.js:1:1:1:24 | import  ... m 'fs'; |
 | tst.js:1:10:1:11 | fs |

javascript/ql/test/library-tests/DataFlow/sources.js

@@ -3,3 +3,5 @@ new (x => x);
 (function(x) {
   return x+19;
 })(23);
+
+/x/;