Revert beforeunload event handler & update test comment

Author: cedrickcooke

compose/ui/ui/src/webCommonW3C/kotlin/androidx/compose/ui/window/ComposeWindow.web.kt

@@ -366,10 +366,6 @@ internal class ComposeWindow(
             lifecycle.handleLifecycleEvent(Lifecycle.Event.ON_PAUSE)
         }
 
-        state.globalEvents.addDisposableEvent("beforeunload") {
-            dispose()
-        }
-
         detachListener.observe(document.body!!, MutationObserverInit(childList = true, subtree = true))
     }
 

compose/ui/ui/src/webTest/kotlin/androidx/compose/ui/window/ComposeWindowLifecycleTest.kt

@@ -62,8 +62,7 @@ class ComposeWindowLifecycleTest : OnCanvasTests {
         window.dispatchEvent(Event("focus"))
         assertEquals(Lifecycle.State.RESUMED, eventsChannel.receive().targetState)
 
-        // An artificial "beforeunload" event crashes the entire test task, so leverage a mutation
-        // for disposing of the ComposeWindow instead.
+        // Implicitly destroy the ComposeWindow by removing its canvas from the DOM.
         canvas.parentNode!!.removeChild(canvas)
         assertEquals(Lifecycle.State.STARTED, eventsChannel.receive().targetState)
         assertEquals(Lifecycle.State.CREATED, eventsChannel.receive().targetState)