[heap,snapshot] Replace first page size from snapshots with page trimming

src/objects.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 4795 matching lines @@
   inline static FreeSpace* cast(HeapObject* obj);
 
   // Dispatched behavior.
   DECLARE_PRINTER(FreeSpace)
   DECLARE_VERIFIER(FreeSpace)
 
   // Layout description.
   // Size is smi tagged when it is stored.
   static const int kSizeOffset = HeapObject::kHeaderSize;
   static const int kNextOffset = POINTER_SIZE_ALIGN(kSizeOffset + kPointerSize);
+  static const int kSize = kNextOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(FreeSpace);
 };
 
 
 // V has parameters (Type, type, TYPE, C type, element_size)
 #define TYPED_ARRAYS(V) \
   V(Uint8, uint8, UINT8, uint8_t, 1)                                           \
   V(Int8, int8, INT8, int8_t, 1)                                               \
@@ skipping 6377 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_