[heap] Fix bad-cast in Sweeper

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index 9c3a1689a1a93f64447394d37217d0c0a675d35a..d3f30158e68eef6f2cd9335eafc797c7b6307494 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -516,8 +516,7 @@ void MarkCompactCollector::Sweeper::StartSweepingHelper(
 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