Remove unnecessary 'null'/'undefined' check, removed temp for args length.

Author: DanielRosenwasser

src/compiler/emitter.ts

@@ -347,9 +347,9 @@ var __extends = (this && this.__extends) || function (d, b) {
 
         const assignHelper = `
 var __assign = (this && this.__assign) || Object.assign || function(t) {
-    for (var i = 1, n = arguments.length; i < n; i++) {
+    for (var i = 1; i < arguments.length; i++) {
         var s = arguments[i];
-        if (s != null) for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
+        for (var p in s) if (s.hasOwnProperty(p)) t[p] = s[p];
     }
     return t;
 };`;