[heap] Minor MC: Add marking

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 50e5ed6969b0f9a8a113fb4fe62bc48335890c18..0e431ddf21ad1d4cc1451b0c013c945ef0fd5263 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -5,6 +5,8 @@
 #ifndef V8_GLOBAL_HANDLES_H_
 #define V8_GLOBAL_HANDLES_H_
 
+#include <vector>
+
 #include "include/v8.h"
 #include "include/v8-profiler.h"
 
@@ -113,6 +115,8 @@ enum WeaknessType {
 
 class GlobalHandles {
  public:
+  enum IterationMode { HANDLE_PHANTOM_NODES, DONT_HANDLE_PHANTOM_NODES };
+
   ~GlobalHandles();
 
   // Creates a new global handle that is alive until Destroy is called.
@@ -227,6 +231,7 @@ class GlobalHandles {
 
   // Iterates over weak independent or unmodified handles.
   // See the note above.
+  template <IterationMode mode>
   void IterateNewSpaceWeakUnmodifiedRoots(ObjectVisitor* v);
 
   // Identify unmodified objects that are in weak state and marks them
@@ -290,7 +295,13 @@ class GlobalHandles {
 #ifdef DEBUG
   void PrintStats();
   void Print();
-#endif
+#endif  // DEBUG
+
+#ifdef VERIFY_HEAP
+  typedef std::vector<std::pair<void*, uint8_t>> NewSpaceNodeStates;
+  NewSpaceNodeStates GetNewSpaceNodeStates();
+  void RestoreNewSpaceNodeStates(const NewSpaceNodeStates& states);
+#endif  // VERIFY_HEAP
 
  private:
   explicit GlobalHandles(Isolate* isolate);