Add a constant to Closure KeyCodes API for FireFox +/* key on German …

…layouts and treats it as a character key for FF.

The close bracket key on US keyboard layouts corresponds to
the +/* key on DE keyboard layouts (the same physical key on
the keyboard produces different outputs depending on keyboard layout).
Firefox sends a unique keycode for this (171), which differs from the
keycode sent by Chrome (221). (See:
https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode)

RELNOTES:Added a keycodes.js constant for the +/* key in Firefox for DE keyboard layouts.
PiperOrigin-RevId: 574474491
Change-Id: Iefdcefa8f4d860c61ffd9e648dc553e871d14fb1

closure/goog/events/keycodes.js

@@ -70,6 +70,8 @@ goog.events.KeyCodes = {
   // SINGLE_QUOTE (US keyboard layout) or SEMICOLON (JP keyboard layout in
   // chrome)
   FF_JP_QUOTE: 58,
+  FF_DE_PLUS: 171,    // Firefox (Gecko) fires this for +/* on DE keyboards
+                      // rather than CLOSE_SQUARE_BRACKET (DE layout in Chrome)
   QUESTION_MARK: 63,  // needs localization
   AT_SIGN: 64,
   A: 65,
@@ -402,6 +404,7 @@ goog.events.KeyCodes.isCharacterKey = function(keyCode) {
     case goog.events.KeyCodes.FF_JP_QUOTE:
       return true;
     case goog.events.KeyCodes.FF_DASH:
+    case goog.events.KeyCodes.FF_DE_PLUS:
       return goog.userAgent.GECKO;
     default:
       return false;