Revert memory saving change due to failures on multithreaded tests

src/serialize.cc

Index: src/serialize.cc
===================================================================
--- src/serialize.cc	(revision 10568)
+++ src/serialize.cc	(working copy)
@@ -612,7 +612,6 @@
     pages_[LO_SPACE].Add(address);
   }
   last_object_address_ = address;
-  ASSERT(address >= Page::FromAddress(address)->ObjectAreaStart());
   return address;
 }
 
@@ -623,12 +622,7 @@
   int offset = source_->GetInt();
   ASSERT(!SpaceIsLarge(space));
   offset <<= kObjectAlignmentBits;
-  Address address = high_water_[space] - offset;
-  // This assert will fail if kMinimumSpaceSizes is too small for a space,
-  // because we rely on the fact that all allocation is linear when the VM
-  // is very young.
-  ASSERT(address >= Page::FromAddress(address)->ObjectAreaStart());
-  return HeapObject::FromAddress(address);
+  return HeapObject::FromAddress(high_water_[space] - offset);
 }