[devtools] Performance recording should wait for model suspension

This CL adds a missing await which causes the performance recording to
now wait until all models are suspended.

Bug: chromium:1000155, chromium:1002427
Change-Id: I4d87159b6c03e52d54f48f4ddaf5a937c4b19751
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1795447
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#696036}

third_party/blink/renderer/devtools/front_end/timeline/TimelineController.js

@@ -187,7 +187,7 @@ Timeline.TimelineController = class {
     // There might be a significant delay in the beginning of timeline recording
     // caused by starting CPU profiler, that needs to traverse JS heap to collect
     // all the functions data.
-    SDK.targetManager.suspendAllTargets();
+    await SDK.targetManager.suspendAllTargets();
     if (enableJSSampling && Runtime.queryParam('timelineTracingJSProfileDisabled'))
       await this._startProfilingOnAllModels();
     if (!this._tracingManager)