--- a/testing/talos/talos/tests/devtools/addon/content/damp.js
+++ b/testing/talos/talos/tests/devtools/addon/content/damp.js
@@ -592,23 +592,20 @@ async _consoleOpenWithCachedMessagesTest
             new Array(${NODES}).join("<div></div>") +
             new Array(${GRID_NODES}).join("<div style='display:grid'></div>");
           content.document.body.appendChild(div);
           sendSyncMessage("setup-test-done");
         }`
       ) + ")()", false);
     });
 
-    // Open the toolbox and record the time.
-    let start = performance.now();
+    // Record the time needed to open the toolbox.
+    let test = this.runTest("inspector.layout.open");
     await this.openToolbox("inspector");
-    this._results.push({
-      name: "inspector.layout.open",
-      value: performance.now() - start
-    });
+    test.done();
 
     await this.closeToolbox();
 
     // Restore sidebar tab preference.
     Services.prefs.setCharPref("devtools.inspector.activeSidebar", sidebarTab);
 
     await this.testTeardown();
   },