Add keyCode attribute to KeyboardEventInit

It's needed to fix cross browsing issue(support IE)

Fixed #15228

Author: taejs

baselines/dom.generated.d.ts

@@ -649,6 +649,7 @@ interface KeyboardEventInit extends EventModifierInit {
     code?: string;
     isComposing?: boolean;
     key?: string;
+    keyCode?: number;
     location?: number;
     repeat?: boolean;
 }

inputfiles/idl/UI Events.widl

@@ -129,6 +129,7 @@ dictionary KeyboardEventInit : EventModifierInit {
   unsigned long location = 0;
   boolean repeat = false;
   boolean isComposing = false;
+  unsigned long keyCode = 0;
 };
 
 [Constructor(DOMString type, optional CompositionEventInit eventInitDict), Exposed=Window]