[heap] Clean-up uses of EnsureSweepingComplete uses.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 06601063791b606d7536612844c7ea4522e621db..ad823c19004daca9f9e300d3dec0de77e4587a9e 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2258,9 +2258,7 @@ void Isolate::Deinit() {
     optimizing_compile_dispatcher_ = NULL;
   }
 
-  if (heap_.mark_compact_collector()->sweeping_in_progress()) {
-    heap_.mark_compact_collector()->EnsureSweepingCompleted();
-  }
+  heap_.mark_compact_collector()->EnsureSweepingCompleted();
 
   DumpAndResetCompilationStats();