ESLint one-var, no-var rules (#3239)

* fixed issues for eslint one-var and no-var rules

Co-authored-by: Joshi <simplyrender@gmail.com>
Co-authored-by: Andrew Henry <akhenry@gmail.com>

src/api/objects/test/RootRegistrySpec.js

@@ -25,10 +25,10 @@ define([
     RootRegistry
 ) {
     describe('RootRegistry', function () {
-        var idA,
-            idB,
-            idC,
-            registry;
+        let idA;
+        let idB;
+        let idC;
+        let registry;
 
         beforeEach(function () {
             idA = {