Add canExceedIdleDeadlineIfRequired function to Scheduler and use it in Oilpan

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index ee4371b6feb516b13100408854cb651b9fcffd96..5b256b690e4996540d2e76705f25d737d0b8948b 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -591,7 +591,9 @@ void ThreadState::performIdleGC(double deadlineSeconds)
         return;
 
     double idleDeltaInSeconds = deadlineSeconds - Platform::current()->monotonicallyIncreasingTime();
-    if (idleDeltaInSeconds <= Heap::estimatedMarkingTime()) {
+    if (idleDeltaInSeconds <= Heap::estimatedMarkingTime() && !Scheduler::shared()->canExceedIdleDeadlineIfRequired()) {
+        // If marking is estimated to take longer than the deadline and we can't
+        // exceed the deadline, then reschedule for the next idle period.
         scheduleIdleGC();
         return;
     }