Revert r14930 and r14935 temporarily.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 78046318a1103bc96c0fb5274114c03d55b6ca8b..c256a7cd9c6cb30c2f435cb93285103d96be3758 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5476,13 +5476,6 @@ class Map: public HeapObject {
   int NumberOfDescribedProperties(DescriptorFlag which = OWN_DESCRIPTORS,
                                   PropertyAttributes filter = NONE);
 
-  // Returns the number of slots allocated for the initial properties
-  // backing storage for instances of this map.
-  int InitialPropertiesLength() {
-    return pre_allocated_property_fields() + unused_property_fields() -
-        inobject_properties();
-  }
-
   // Casting.
   static inline Map* cast(Object* obj);