[heap] Fix bad-cast in Sweeper

src/heap/mark-compact.cc

 // Copyright 2012 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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 498 matching lines @@
     AllocationSpace space_to_start) {
   num_sweeping_tasks_.Increment(1);
   V8::GetCurrentPlatform()->CallOnBackgroundThread(
       new SweeperTask(this, &pending_sweeper_tasks_semaphore_, space_to_start),
       v8::Platform::kShortRunningTask);
 }
 
 void MarkCompactCollector::Sweeper::SweepOrWaitUntilSweepingCompleted(
     Page* page) {
   if (!page->SweepingDone()) {
-    PagedSpace* owner = reinterpret_cast<PagedSpace*>(page->owner());
-    ParallelSweepPage(page, owner->identity());
+    ParallelSweepPage(page, page->owner()->identity());
     if (!page->SweepingDone()) {
       // We were not able to sweep that page, i.e., a concurrent
       // sweeper thread currently owns this page. Wait for the sweeper
       // thread to be done with this page.
       page->WaitUntilSweepingCompleted();
     }
   }
 }
 
 void MarkCompactCollector::SweepAndRefill(CompactionSpace* space) {
@@ skipping 3562 matching lines @@
     MarkBit mark_bit = Marking::MarkBitFrom(host);
     if (Marking::IsBlack(mark_bit)) {
       RelocInfo rinfo(isolate(), pc, RelocInfo::CODE_TARGET, 0, host);
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8