fix JS lint errors

Author: fhinkel

test/parallel/test-vm-global-configurable-properties.js

@@ -7,9 +7,9 @@ const vm = require('vm');
 
 const ctx = vm.createContext();
 
-let window = vm.runInContext("this", ctx);
+const window = vm.runInContext('this', ctx);
 
-Object.defineProperty(window, "x", { value: "1",  configurable: true});
-assert.strictEqual(window.x, "1");
-Object.defineProperty(window, "x", { value: "2",  configurable: true });
-assert.strictEqual(window.x, "2");
+Object.defineProperty(window, 'x', { value: '1', configurable: true });
+assert.strictEqual(window.x, '1');
+Object.defineProperty(window, 'x', { value: '2', configurable: true });
+assert.strictEqual(window.x, '2');