Revert "Precisely sweeping of scan-on-scavenge pages."

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index dbb11746c5801c48e832671f5bf02e34a1f530f8..56b0da8b836c07e347af658cfb028594ea2cc705 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -4161,23 +4161,12 @@ void MarkCompactCollector::SweepSpace(PagedSpace* space, SweeperType sweeper) {
           pages_swept++;
           parallel_sweeping_active = true;
         } else {
-          if (p->scan_on_scavenge()) {
-            SweepPrecisely<SWEEP_ONLY, IGNORE_SKIP_LIST, IGNORE_FREE_SPACE>(
-                space, p, NULL);
-            pages_swept++;
-            if (FLAG_gc_verbose) {
-              PrintF("Sweeping 0x%" V8PRIxPTR
-                  " scan on scavenge page precisely.\n",
-                  reinterpret_cast<intptr_t>(p));
-            }
-          } else {
-            if (FLAG_gc_verbose) {
-              PrintF("Sweeping 0x%" V8PRIxPTR " conservatively in parallel.\n",
-                  reinterpret_cast<intptr_t>(p));
-            }
-            p->set_parallel_sweeping(MemoryChunk::PARALLEL_SWEEPING_PENDING);
-            space->IncreaseUnsweptFreeBytes(p);
+          if (FLAG_gc_verbose) {
+            PrintF("Sweeping 0x%" V8PRIxPTR " conservatively in parallel.\n",
+                   reinterpret_cast<intptr_t>(p));
           }
+          p->set_parallel_sweeping(MemoryChunk::PARALLEL_SWEEPING_PENDING);
+          space->IncreaseUnsweptFreeBytes(p);
         }
         space->set_end_of_unswept_pages(p);
         break;