Fix http://bugzilla.mozilla.org/show_bug.cgi?id=194364:

no assignment of function expression statements to script result

js/rhino/src/org/mozilla/javascript/IRFactory.java

@@ -102,6 +102,10 @@ public class IRFactory {
         return new Node(TokenStream.EXPRSTMT, (Node) expr, lineno);
     }
 
+    public Object createExprStatementNoReturn(Object expr, int lineno) {
+        return new Node(TokenStream.POP, (Node) expr, lineno);
+    }
+
     /**
      * Name
      */

js/rhino/src/org/mozilla/javascript/Parser.java

@@ -300,7 +300,7 @@ class Parser {
                 // The following can be removed but then code generators should
                 // be modified not to push on the stack function expression
                 // statements
-                pn = nf.createExprStatement(pn, baseLineno);
+                pn = nf.createExprStatementNoReturn(pn, baseLineno);
             }
             // Add EOL but only if function is not part of expression, in which
             // case it gets SEMI + EOL from Statement.