Revert "Allow partial scanning of large arrays in order to avoid"

src/spaces.h

Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index 97bcaa59ab4a6e0d4b31a2a954c292cdbfae5a35..effe06b031ac960f2cf5fc58904ca7bd573ced8c 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -400,15 +400,6 @@ class MemoryChunk {
     WAS_SWEPT_PRECISELY,
     WAS_SWEPT_CONSERVATIVELY,
 
-    // Used for large objects only.  Indicates that the object has been
-    // partially scanned by the incremental mark-sweep GC.  Objects that have
-    // been partially scanned are marked black so that the write barrier
-    // triggers for them, and they are counted as live bytes.  If the mutator
-    // writes to them they may be turned grey and subtracted from the live byte
-    // list.  They move back to the marking deque either by an iteration over
-    // the large object space or in the write barrier.
-    IS_PARTIALLY_SCANNED,
-
     // Last flag, keep at bottom.
     NUM_MEMORY_CHUNK_FLAGS
   };
@@ -429,25 +420,6 @@ class MemoryChunk {
       (1 << IN_FROM_SPACE) |
       (1 << IN_TO_SPACE);
 
-  static const int kIsPartiallyScannedMask = 1 << IS_PARTIALLY_SCANNED;
-
-  void SetPartiallyScannedProgress(int progress) {
-    SetFlag(IS_PARTIALLY_SCANNED);
-    partially_scanned_progress_ = progress;
-  }
-
-  bool IsPartiallyScanned() {
-    return IsFlagSet(IS_PARTIALLY_SCANNED);
-  }
-
-  void SetCompletelyScanned() {
-    ClearFlag(IS_PARTIALLY_SCANNED);
-  }
-
-  int PartiallyScannedProgress() {
-    ASSERT(IsPartiallyScanned());
-    return partially_scanned_progress_;
-  }
 
   void SetFlag(int flag) {
     flags_ |= static_cast<uintptr_t>(1) << flag;
@@ -534,14 +506,8 @@ class MemoryChunk {
 
   static const size_t kWriteBarrierCounterOffset =
       kSlotsBufferOffset + kPointerSize + kPointerSize;
-  static const size_t kPartiallyScannedProgress =
-      kWriteBarrierCounterOffset + kPointerSize;
 
-  // Actually the partially_scanned_progress_ member is only an int, but on
-  // 64 bit the size of MemoryChunk gets rounded up to a 64 bit size so we
-  // have to have the header start kPointerSize after the
-  // partially_scanned_progress_ member.
-  static const size_t kHeaderSize = kPartiallyScannedProgress + kPointerSize;
+  static const size_t kHeaderSize = kWriteBarrierCounterOffset + kPointerSize;
 
   static const int kBodyOffset =
     CODE_POINTER_ALIGN(MAP_POINTER_ALIGN(kHeaderSize + Bitmap::kSize));
@@ -678,7 +644,6 @@ class MemoryChunk {
   SlotsBuffer* slots_buffer_;
   SkipList* skip_list_;
   intptr_t write_barrier_counter_;
-  int partially_scanned_progress_;
 
   static MemoryChunk* Initialize(Heap* heap,
                                  Address base,