fix: fix keyName checking for arrow keys in IE11

fix #7806

src/compiler/codegen/events.js

@@ -22,10 +22,11 @@ const keyNames: { [key: string]: string | Array<string> } = {
   tab: 'Tab',
   enter: 'Enter',
   space: ' ',
-  up: 'ArrowUp',
-  left: 'ArrowLeft',
-  right: 'ArrowRight',
-  down: 'ArrowDown',
+  // #7806: IE11 uses key names without `Arrow` prefix for arrow keys.
+  up: ['Up', 'ArrowUp'],
+  left: ['Left', 'ArrowLeft'],
+  right: ['Right', 'ArrowRight'],
+  down: ['Down', 'ArrowDown'],
   'delete': ['Backspace', 'Delete']
 }