Reland concurrent sweeping of code space.

src/heap/store-buffer.cc

Index: src/heap/store-buffer.cc
diff --git a/src/heap/store-buffer.cc b/src/heap/store-buffer.cc
index a5191dc748e34e944b015b52c67207c6ba537553..a1968442541d166f33281e62644d1272d806200c 100644
--- a/src/heap/store-buffer.cc
+++ b/src/heap/store-buffer.cc
@@ -468,16 +468,8 @@ void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
               }
             }
           } else {
-            if (!page->SweepingCompleted()) {
-              heap_->mark_compact_collector()->SweepInParallel(page, owner);
-              if (!page->SweepingCompleted()) {
-                // We were not able to sweep that page, i.e., a concurrent
-                // sweeper thread currently owns this page. Wait for the sweeper
-                // thread to be done with this page.
-                page->WaitUntilSweepingCompleted();
-              }
-            }
-            CHECK(page->owner() == heap_->old_space());
+            heap_->mark_compact_collector()->SweepOrWaitUntilSweepingCompleted(
+                page);
             HeapObjectIterator iterator(page, NULL);
             for (HeapObject* heap_object = iterator.Next(); heap_object != NULL;
                  heap_object = iterator.Next()) {