Port null/undefined support in __rest from microsoft/TypeScript#12552

Author: mhegazy

tslib.es6.js

@@ -31,7 +31,7 @@ export function __rest(s, e) {
     var t = {};
     for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
         t[p] = s[p];
-    if (typeof Object.getOwnPropertySymbols === "function")
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
         for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
             t[p[i]] = s[p[i]];
     return t;

tslib.js

@@ -62,7 +62,7 @@ var __generator;
         var t = {};
         for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
             t[p] = s[p];
-        if (typeof Object.getOwnPropertySymbols === "function")
+        if (s != null && typeof Object.getOwnPropertySymbols === "function")
             for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) if (e.indexOf(p[i]) < 0)
                 t[p[i]] = s[p[i]];
         return t;