[heap] Fix checks in NewSpace::EnsureAllocation.

src/heap/spaces.cc

 // Copyright 2011 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.
 
 #include "src/heap/spaces.h"
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/heap/slot-set.h"
@@ skipping 1483 matching lines @@
 }
 
 
 bool NewSpace::EnsureAllocation(int size_in_bytes,
                                 AllocationAlignment alignment) {
   Address old_top = allocation_info_.top();
   Address high = to_space_.page_high();
   int filler_size = Heap::GetFillToAlign(old_top, alignment);
   int aligned_size_in_bytes = size_in_bytes + filler_size;
 
-  if (old_top + aligned_size_in_bytes >= high) {
+  if (old_top + aligned_size_in_bytes > high) {
     // Not enough room in the page, try to allocate a new one.
     if (!AddFreshPage()) {
       return false;
     }
 
     InlineAllocationStep(old_top, allocation_info_.top(), nullptr, 0);
 
     old_top = allocation_info_.top();
     high = to_space_.page_high();
     filler_size = Heap::GetFillToAlign(old_top, alignment);
-    aligned_size_in_bytes = size_in_bytes + filler_size;
   }
 
-  DCHECK(old_top + aligned_size_in_bytes < high);
+  DCHECK(old_top + aligned_size_in_bytes <= high);
 
   if (allocation_info_.limit() < high) {
     // Either the limit has been lowered because linear allocation was disabled
     // or because incremental marking wants to get a chance to do a step,
     // or because idle scavenge job wants to get a chance to post a task.
     // Set the new limit accordingly.
     Address new_top = old_top + aligned_size_in_bytes;
     Address soon_object = old_top + filler_size;
     InlineAllocationStep(new_top, new_top, soon_object, size_in_bytes);
     UpdateInlineAllocationLimit(aligned_size_in_bytes);
@@ skipping 1598 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8