Move sweeping pending status field of concurrent sweepers to MarkCompactCollector.

src/sweeper-thread.cc

Index: src/sweeper-thread.cc
diff --git a/src/sweeper-thread.cc b/src/sweeper-thread.cc
index 0e60c3eb82928add84ec7274a87396d4a3f6c5b2..df5fcc683a403770ccaedfd9e4ef57d3e20b2472 100644
--- a/src/sweeper-thread.cc
+++ b/src/sweeper-thread.cc
@@ -54,9 +54,6 @@ SweeperThread::SweeperThread(Isolate* isolate)
 }
 
 
-bool SweeperThread::sweeping_pending_ = false;
-
-
 void SweeperThread::Run() {
   Isolate::SetIsolateThreadLocals(isolate_, NULL);
   while (true) {
@@ -77,6 +74,7 @@ void SweeperThread::Run() {
   }
 }
 
+
 intptr_t SweeperThread::StealMemory(PagedSpace* space) {
   intptr_t free_bytes = 0;
   if (space->identity() == OLD_POINTER_SPACE) {