some updates on focustrap (based on #35165)

js/src/util/focustrap.js

@@ -7,6 +7,7 @@
 
 import EventHandler from '../dom/event-handler'
 import SelectorEngine from '../dom/selector-engine'
+import { getDocument } from './index'
 import Config from './config'
 
 /**
@@ -43,6 +44,7 @@ class FocusTrap extends Config {
     this._config = this._getConfig(config)
     this._isActive = false
     this._lastTabNavDirection = null
+    this._document = getDocument()
   }
 
   // Getters
@@ -68,9 +70,9 @@ class FocusTrap extends Config {
       this._config.trapElement.focus()
     }
 
-    EventHandler.off(document, EVENT_KEY) // guard against infinite focus loop
-    EventHandler.on(document, EVENT_FOCUSIN, event => this._handleFocusin(event))
-    EventHandler.on(document, EVENT_KEYDOWN_TAB, event => this._handleKeydown(event))
+    EventHandler.off(this._document, EVENT_KEY) // guard against infinite focus loop
+    EventHandler.on(this._document, EVENT_FOCUSIN, event => this._handleFocusin(event))
+    EventHandler.on(this._document, EVENT_KEYDOWN_TAB, event => this._handleKeydown(event))
 
     this._isActive = true
   }
@@ -81,14 +83,14 @@ class FocusTrap extends Config {
     }
 
     this._isActive = false
-    EventHandler.off(document, EVENT_KEY)
+    EventHandler.off(this._document, EVENT_KEY)
   }
 
   // Private
   _handleFocusin(event) {
     const { trapElement } = this._config
 
-    if (event.target === document || event.target === trapElement || trapElement.contains(event.target)) {
+    if (event.target === this._document || event.target === trapElement || trapElement.contains(event.target)) {
       return
     }