Use the scheduling mechanism provided by the platform

Source/platform/ThreadTimers.cpp

Index: Source/platform/ThreadTimers.cpp
diff --git a/Source/platform/ThreadTimers.cpp b/Source/platform/ThreadTimers.cpp
index 0cc2ac15b644033a6f2d56c7ae000c1778b37fa6..25d14afa5c896245ddacd0ffb9b293c1d935bb3e 100644
--- a/Source/platform/ThreadTimers.cpp
+++ b/Source/platform/ThreadTimers.cpp
@@ -31,7 +31,8 @@
 #include "platform/SharedTimer.h"
 #include "platform/Timer.h"
 #include "platform/TraceEvent.h"
-#include "platform/scheduler/Scheduler.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebScheduler.h"
 #include "wtf/CurrentTime.h"
 #include "wtf/MainThread.h"
 
@@ -137,7 +138,11 @@ void ThreadTimers::sharedTimerFiredInternal()
         timer.fired();
 
         // Catch the case where the timer asked timers to fire in a nested event loop, or we are over time limit.
-        if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime() || (isMainThread() && Scheduler::shared()->shouldYieldForHighPriorityWork()))
+        if (!m_firingTimers || timeToQuit < monotonicallyIncreasingTime())
+            break;
+
+        // Yield if there is more critical work pending on the main thread.
+        if ((isMainThread() && Platform::current()->scheduler() && Platform::current()->scheduler()->shouldYieldForHighPriorityWork()))
             break;
     }