Bug 1625137 - Fix perma-failing browser_dbg-tabs-without-urls-selected test r=jlast

Differential Revision: https://phabricator.services.mozilla.com/D68382

--HG--
extra : moz-landing-system : lando

devtools/client/debugger/test/mochitest/browser_dbg-tabs-without-urls-selected.js

@@ -16,8 +16,10 @@ add_task(async function() {
   await waitForPaused(dbg);
 
   // Click a frame which shouldn't open a new source tab
-  await clickElement(dbg, "frame", 2);
+  await clickElement(dbg, "frame", 3);
 
   // Click the frame to select the same location and ensure there's only 1 tab
   is(countTabs(dbg), 1);
+
+  await resume(dbg);
 });