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

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index 99a50487f9c457465c8879f9efd20bd08d569eb7..843e73d8e7dfa7d026036e70a8c80d9cd206204f 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -504,9 +504,6 @@ class ThreadLocalTop;
 // Mark-Compact collector
 class MarkCompactCollector {
  public:
-  // Set the global flags, it must be called before Prepare to take effect.
-  inline void SetFlags(int flags);
-
   static void Initialize();
 
   void SetUp();
@@ -600,12 +597,6 @@ class MarkCompactCollector {
 
   void ClearMarkbits();
 
-  bool abort_incremental_marking() const { return abort_incremental_marking_; }
-
-  bool finalize_incremental_marking() const {
-    return finalize_incremental_marking_;
-  }
-
   bool is_compacting() const { return compacting_; }
 
   MarkingParity marking_parity() { return marking_parity_; }
@@ -703,12 +694,6 @@ class MarkCompactCollector {
   CollectorState state_;
 #endif
 
-  bool reduce_memory_footprint_;
-
-  bool abort_incremental_marking_;
-
-  bool finalize_incremental_marking_;
-
   MarkingParity marking_parity_;
 
   // True if we are collecting slots to perform evacuation from evacuation