Worker: Remove outdated comments from SharedWorkerReportingProxy

This CL removes an outdated comment about off-the-main-thread shared
worker script fetch that is already enabled by default.

Bug: 924041
Change-Id: I6b1bc606be04be2e80b9ef52370b3d58ce794b81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2162394
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Auto-Submit: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762151}

third_party/blink/renderer/core/workers/shared_worker_reporting_proxy.cc

@@ -64,9 +64,6 @@ void SharedWorkerReportingProxy::ReportConsoleMessage(
 }
 
 void SharedWorkerReportingProxy::DidFailToFetchClassicScript() {
-  // TODO(nhiroki): Add a runtime flag check for off-the-main-thread shared
-  // worker script fetch. This function should be called only when the flag is
-  // enabled (https://crbug.com/924041).
   DCHECK(!IsMainThread());
   PostCrossThreadTask(
       *parent_execution_context_task_runners_->Get(TaskType::kInternalDefault),