Bug 1435829 - Part 5: Update xray tests for RegExp.prototype. r=peterv

js/xpconnect/tests/chrome/test_xrayToJS.xul

@@ -244,6 +244,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
     ["constructor", "toSource", "toString", "compile", "exec", "test",
      Symbol.match, Symbol.replace, Symbol.search, Symbol.split,
      "flags", "global", "ignoreCase", "multiline", "source", "sticky", "unicode"];
+  if (isNightlyBuild) {
+    gPrototypeProperties['RegExp'].push(Symbol.matchAll);
+  }
   gConstructorProperties['RegExp'] =
     constructorProps(["input", "lastMatch", "lastParen",
                       "leftContext", "rightContext", "$1", "$2", "$3", "$4",