[Isolates] Pass isolate to VMState constructor.

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index 8560e93b2af3c553b2ae19b8abfbdf543fd3e64a..d33526dbe043e880eba43c42afd1b3626e99b9b8 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -138,11 +138,13 @@ class GlobalHandles {
 #endif
   class Pool;
  private:
-  GlobalHandles();
+  explicit GlobalHandles(Isolate* isolate);
 
   // Internal node structure, one for each global handle.
   class Node;
 
+  Isolate* isolate_;
+
   // Field always containing the number of weak and near-death handles.
   int number_of_weak_handles_;