Fix typo in comment.

Change-Id: I0ed01ce85cc0c4bd5e1c9475e47fd19771d714e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2147406
Auto-Submit: Tal Pressman <talp@chromium.org>
Commit-Queue: Alexander Timin <altimin@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759217}

third_party/blink/renderer/platform/scheduler/main_thread/page_scheduler_impl.h

@@ -96,7 +96,7 @@ class PLATFORM_EXPORT PageSchedulerImpl : public PageScheduler {
 
   bool IsLoading() const;
 
-  // An "ordinary" PageScheduler is responsible for is a fully-featured page
+  // An "ordinary" PageScheduler is responsible for a fully-featured page
   // owned by a web view.
   bool IsOrdinary() const;