test: run script to help target discovery and reduce flakes (#44741)

spec/api-debugger-spec.ts

@@ -227,21 +227,26 @@ describe('debugger module', () => {
     it('creates unique session id for each target', (done) => {
       w.webContents.loadFile(path.join(__dirname, 'fixtures', 'sub-frames', 'debug-frames.html'));
       w.webContents.debugger.attach();
-      let session: String;
+      let debuggerSessionId: string;
 
       w.webContents.debugger.on('message', (event, ...args) => {
         const [method, params, sessionId] = args;
         if (method === 'Target.targetCreated') {
           w.webContents.debugger.sendCommand('Target.attachToTarget', { targetId: params.targetInfo.targetId, flatten: true }).then(result => {
-            session = result.sessionId;
+            debuggerSessionId = result.sessionId;
             w.webContents.debugger.sendCommand('Debugger.enable', {}, result.sessionId);
+
+            // Ensure debugger finds a script to pause to possibly reduce flaky
+            // tests.
+            w.webContents.mainFrame.executeJavaScript('void 0;');
           });
         }
         if (method === 'Debugger.scriptParsed') {
-          expect(sessionId).to.equal(session);
+          if (sessionId === debuggerSessionId) {
             w.webContents.debugger.detach();
             done();
           }
+        }
       });
       w.webContents.debugger.sendCommand('Target.setDiscoverTargets', { discover: true });
     });