Use a dictionary-mode code cache on the map rather than a dual system.

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 99741170bcb74adb0f2fe0440a21eee358c6e8cd..f05f516a7b15db5281732e728c2587cf60bbddac 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -554,12 +554,6 @@ void IncrementalMarking::StartMarking() {
   heap_->CompletelyClearInstanceofCache();
   heap_->isolate()->compilation_cache()->MarkCompactPrologue();
 
-  if (FLAG_cleanup_code_caches_at_gc) {
-    // We will mark cache black with a separate pass
-    // when we finish marking.
-    MarkObjectGreyDoNotEnqueue(heap_->polymorphic_code_cache());
-  }
-
   // Mark strong roots grey.
   IncrementalMarkingRootMarkingVisitor visitor(this);
   heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
@@ -926,13 +920,6 @@ void IncrementalMarking::Hurry() {
     }
   }
 
-  if (FLAG_cleanup_code_caches_at_gc) {
-    PolymorphicCodeCache* poly_cache = heap_->polymorphic_code_cache();

[mvstanton, 2016/04/05 13:10:43]

Holy cow, it's good to get rid of this gc-specific stuff for a cache. :/

-    Marking::GreyToBlack(Marking::MarkBitFrom(poly_cache));
-    MemoryChunk::IncrementLiveBytesFromGC(poly_cache,
-                                          PolymorphicCodeCache::kSize);
-  }
-
   Object* context = heap_->native_contexts_list();
   while (!context->IsUndefined()) {
     // GC can happen when the context is not fully initialized,