Modify layout test for closing the Request Details panel

The 'Escape' key is used in multiple keybinds that collide with each other
and thus, the action that is effectively triggered cannot be known
beforehand. This test relied on the usage of such key and on the specific
order in which actions were loaded. Now, with the migration of extensions
out of module.json files, the order for loading actions is altered and this
tests starts failing in consequence.

This change modifies the test so that the tested behaviour is triggered
without relying on the usage of the 'Escape' key.

Bug: 1134103
Change-Id: I508704d4507f24441988a837c06f5c009817a91a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2586533Reviewed-by: Tim van der Lippe <tvanderlippe@chromium.org>
Commit-Queue: Andres Olivares <andoli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836632}

third_party/blink/web_tests/http/tests/devtools/network/network-close-request-view.js

@@ -18,8 +18,7 @@
   TestRunner.addResult('Network Item View: ' + (panel._networkItemView && panel._networkItemView.isShowing()));
 
   TestRunner.addResult('Hiding request');
-  eventSender.keyDown('Escape');
-  await TestRunner.addSnifferPromise(Network.NetworkPanel.ActionDelegate.prototype, 'handleAction')
+  panel._hideRequestPanel();
   TestRunner.addResult('Network Item View: ' + (panel._networkItemView && panel._networkItemView.isShowing()));
 
   TestRunner.completeTest();