Force incremental marking when called from idle notification.

src/incremental-marking.cc

Index: src/incremental-marking.cc
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index 0ab9a002452e94aa7846816d14c73e9c4f349b7e..c98f117c24622c000593c67d72ab41c069ebf495 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -834,8 +834,8 @@ void IncrementalMarking::OldSpaceStep(intptr_t allocated) {
 }
 
 
-void IncrementalMarking::Step(intptr_t allocated_bytes,
-                              CompletionAction action) {
+void IncrementalMarking::Step(intptr_t allocated_bytes, CompletionAction action,
+                              bool force_marking) {
   if (heap_->gc_state() != Heap::NOT_IN_GC ||
       !FLAG_incremental_marking ||
       !FLAG_incremental_marking_steps ||
@@ -845,7 +845,7 @@ void IncrementalMarking::Step(intptr_t allocated_bytes,
 
   allocated_ += allocated_bytes;
 
-  if (allocated_ < kAllocatedThreshold &&
+  if (!force_marking && allocated_ < kAllocatedThreshold &&
       write_barriers_invoked_since_last_step_ <
           kWriteBarriersInvokedThreshold) {
     return;