[heap] Cleanup and fix GC flags / add testing infra

src/heap/mark-compact-inl.h

Index: src/heap/mark-compact-inl.h
diff --git a/src/heap/mark-compact-inl.h b/src/heap/mark-compact-inl.h
index 37a0f88fdab78d2383677bebb89ca2f6d1ef4c3f..6372c2eeea38c1d4cf9d95c8e89dd0685088c4ed 100644
--- a/src/heap/mark-compact-inl.h
+++ b/src/heap/mark-compact-inl.h
@@ -11,17 +11,6 @@
 namespace v8 {
 namespace internal {
 
-
-void MarkCompactCollector::SetFlags(int flags) {
-  reduce_memory_footprint_ = ((flags & Heap::kReduceMemoryFootprintMask) != 0);
-  abort_incremental_marking_ =
-      ((flags & Heap::kAbortIncrementalMarkingMask) != 0);
-  finalize_incremental_marking_ =
-      ((flags & Heap::kFinalizeIncrementalMarkingMask) != 0);
-  DCHECK(!finalize_incremental_marking_ || !abort_incremental_marking_);
-}
-
-
 void MarkCompactCollector::PushBlack(HeapObject* obj) {
   DCHECK(Marking::IsBlack(Marking::MarkBitFrom(obj)));
   if (marking_deque_.Push(obj)) {