Avoid use of 'let' and 'const'

They are not supported on older browsers, e.g. iOS 9.

core/input/devices.js

@@ -19,7 +19,7 @@ import KeyTable from "./keysym.js";
 // Keyboard event handler
 //
 
-const Keyboard = function (defaults) {
+function Keyboard(defaults) {
     this._keyDownList = {};         // List of depressed keys
                                     // (even if they are happy)
     this._pendingKey = null;        // Key waiting for keypress
@@ -276,7 +276,7 @@ make_properties(Keyboard, [
     ['onKeyEvent', 'rw', 'func'] // Handler for key press/release
 ]);
 
-const Mouse = function (defaults) {
+function Mouse(defaults) {
 
     this._doubleClickTimer = null;
     this._lastTouchPos = null;

core/util/events.js

@@ -24,7 +24,7 @@ export function stopEvent (e) {
 // Emulate Element.setCapture() when not supported
 var _captureRecursion = false;
 var _captureElem = null;
-const _captureProxy = function (e) {
+function _captureProxy(e) {
     // Recursion protection as we'll see our own event
     if (_captureRecursion) return;
 
@@ -50,11 +50,11 @@ const _captureProxy = function (e) {
 };
 
 // Follow cursor style of target element
-const _captureElemChanged = function() {
+function _captureElemChanged() {
     var captureElem = document.getElementById("noVNC_mouse_capture_elem");
     captureElem.style.cursor = window.getComputedStyle(_captureElem).cursor;
 };
-const _captureObserver = new MutationObserver(_captureElemChanged);
+var _captureObserver = new MutationObserver(_captureElemChanged);
 
 var _captureIndex = 0;
 

core/util/localization.js

@@ -153,7 +153,7 @@ Localizer.prototype = {
             }
 
             for (var i = 0;i < elem.childNodes.length;i++) {
-                let node = elem.childNodes[i];
+                var node = elem.childNodes[i];
                 if (node.nodeType === node.ELEMENT_NODE) {
                     process(node, enabled);
                 } else if (node.nodeType === node.TEXT_NODE && enabled) {
@@ -166,5 +166,5 @@ Localizer.prototype = {
     },
 }
 
-export const l10n = new Localizer();
+export var l10n = new Localizer();
 export default l10n.get.bind(l10n);