removed code, redundant with line 428 (playcanvas#1099)

Tatsujinichi · willeastcott · commit 7392a3efcd5d · 2018-02-20T19:35:00.000-08:00
diff --git a/src/framework/components/script/component.js b/src/framework/components/script/component.js
@@ -437,7 +437,6 @@ pc.extend(pc, function () {
             // remove swap event
             this.system.app.scripts.off('swap:' + scriptName, scriptData.onSwap);
 
-            delete this._scriptsIndex[scriptName];
             delete this[scriptName];
 
             this.fire('destroy', scriptName, scriptData.instance || null);
