Use kUserInteraction task source for Pointer Lock events

kUserInteraction task source will align the pointer lock events with the
mouse events. It will also help spec consistency.

Bug: 1109007
Change-Id: I6426874161fc772a27640831617e70f941737b2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316808Reviewed-by: James Hollyer <jameshollyer@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: James Hollyer <jameshollyer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791978}

third_party/blink/renderer/core/page/pointer_lock_controller.cc

@@ -328,7 +328,7 @@ void PointerLockController::EnqueueEvent(const AtomicString& type,
                                          Document* document) {
   if (document && document->domWindow()) {
     document->domWindow()->EnqueueDocumentEvent(*Event::Create(type),
-                                                TaskType::kMiscPlatformAPI);
+                                                TaskType::kUserInteraction);
   }
 }