GUACAMOLE-447: Merge add UIKit key constants sometimes (incorrectly) used by iOS Safari.

guacamole-common-js/src/main/webapp/modules/Keyboard.js

@@ -498,6 +498,11 @@ Guacamole.Keyboard = function(element) {
         "SingleCandidate": [0xFF3C],
         "Super": [0xFFEB, 0xFFEB, 0xFFEC],
         "Tab": [0xFF09],
+        "UIKeyInputDownArrow": [0xFF54],
+        "UIKeyInputEscape": [0xFF1B],
+        "UIKeyInputLeftArrow": [0xFF51],
+        "UIKeyInputRightArrow": [0xFF53],
+        "UIKeyInputUpArrow": [0xFF52],
         "Up": [0xFF52],
         "Undo": [0xFF65],
         "Win": [0xFFEB],