Stop using keyboardinputReset at the start of keyInput

* This fixes backspace when using the on-screen keyboard on Android

include/ui.js

@@ -961,11 +961,7 @@ var UI;
             if (!UI.rfb) return;
 
             var newValue = event.target.value;
-
-            if (!UI.lastKeyboardinput) {
-                UI.keyboardinputReset();
-            }
-            var oldvalue = UI.lastKeyboardinput;
+            var oldValue = UI.lastKeyboardinput;
 
             var newLen;
             try {