[heap] Unify MarkingDeque push and unshift operations.

test/cctest/test-mark-compact.cc

Index: test/cctest/test-mark-compact.cc
diff --git a/test/cctest/test-mark-compact.cc b/test/cctest/test-mark-compact.cc
index d54e0afd83213d579bc69263d771cf975ec66cfe..73369d29e57fa7a4c31dd86ac1fd026abbea5838 100644
--- a/test/cctest/test-mark-compact.cc
+++ b/test/cctest/test-mark-compact.cc
@@ -59,7 +59,7 @@ TEST(MarkingDeque) {
   Address original_address = reinterpret_cast<Address>(&s);
   Address current_address = original_address;
   while (!s.IsFull()) {
-    s.PushBlack(HeapObject::FromAddress(current_address));
+    s.Push(HeapObject::FromAddress(current_address));
     current_address += kPointerSize;
   }