Reset context disposed counter after executing the idle garbage collection operation.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 1f7d8784f6b8fbf104e121212fc6e5c2b28a9196..84751c55aabebad7440fcd19b63e0ae2ebb09e72 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4316,7 +4316,6 @@ bool Heap::IdleNotification(int idle_time_in_ms) {
   GCIdleTimeAction action =
       gc_idle_time_handler_.Compute(idle_time_in_ms, heap_state);
 
-  contexts_disposed_ = 0;
   bool result = false;
   switch (action.type) {
     case DO_INCREMENTAL_MARKING:
@@ -4352,6 +4351,7 @@ bool Heap::IdleNotification(int idle_time_in_ms) {
     PrintF("]\n");
   }
 
+  contexts_disposed_ = 0;
   return result;
 }