Revert "Merge old data and pointer space."

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 706c06496fef1313552ecea4387cf3970db95eea..cf6d1613e6545724162d07b7fa22e4ab759f58c6 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -763,7 +763,7 @@ enum InstanceType {
   // Boundaries for testing for a fixed typed array.
   FIRST_FIXED_TYPED_ARRAY_TYPE = FIXED_INT8_ARRAY_TYPE,
   LAST_FIXED_TYPED_ARRAY_TYPE = FIXED_UINT8_CLAMPED_ARRAY_TYPE,
-  // Boundary for promotion to old space.
+  // Boundary for promotion to old data space/old pointer space.
   LAST_DATA_TYPE = FILLER_TYPE,
   // Boundary for objects represented as JSReceiver (i.e. JSObject or JSProxy).
   // Note that there is no range for JSObject or JSProxy, since their subtypes
@@ -10266,6 +10266,8 @@ class JSDataView: public JSArrayBufferView {
 
 
 // Foreign describes objects pointing from JavaScript to C structures.
+// Since they cannot contain references to JS HeapObjects they can be
+// placed in old_data_space.
 class Foreign: public HeapObject {
  public:
   // [address]: field containing the address.