Adding freelist statistics to blink gc dump provider.

Source/platform/heap/ThreadState.h

Index: Source/platform/heap/ThreadState.h
diff --git a/Source/platform/heap/ThreadState.h b/Source/platform/heap/ThreadState.h
index 45b45bf5fe06307a0662e8690afac5d131055572..56f9e15ee73462e93a0af440a557b1c91f5cd442 100644
--- a/Source/platform/heap/ThreadState.h
+++ b/Source/platform/heap/ThreadState.h
@@ -642,6 +642,11 @@ public:
     void promptlyFreed(size_t gcInfoIndex);
 
 private:
+    enum SnapshotType {
+        HeapSnapshot,
+        FreelistSnapshot
+    };
+
     ThreadState();
     ~ThreadState();
 
@@ -689,7 +694,7 @@ private:
     void unregisterPreFinalizerInternal(void*);
     void invokePreFinalizers();
 
-    void takeSnapshot();
+    void takeSnapshot(SnapshotType);
 #if ENABLE(GC_PROFILING)
     void snapshotFreeList();
 #endif