Fix logic for doing incremental marking steps on tenured allocation.

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index 749fa5ef54934d7c2ed3945d8381b4cfd3c2cdcb..79e5590a6c0304dad076fb674cad3f6d0c403137 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -838,7 +838,7 @@ void IncrementalMarking::OldSpaceStep(intptr_t allocated) {
     // in principle possible.
     Start(PREVENT_COMPACTION);

[Erik Corry Chromium.org, 2015/03/31 13:11:32]

Time to revisit this TODO if we didn't already today?

[Hannes Payer (out of office), 2015/04/02 13:36:39]

Done.

   } else {
-    Step(allocated * kFastMarking / kInitialMarkingSpeed, GC_VIA_STACK_GUARD);
+    Step(allocated * kOldSpaceAllocationMarkingFactor, GC_VIA_STACK_GUARD);
   }
 }
 
@@ -914,8 +914,7 @@ intptr_t IncrementalMarking::Step(intptr_t allocated_bytes,
                                   ForceMarkingAction marking,
                                   ForceCompletionAction completion) {
   if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking ||
-      !FLAG_incremental_marking_steps ||
-      (state_ != SWEEPING && state_ != MARKING)) {
+      !CanDoSteps()) {
     return 0;
   }