[Isolates] Pass current isolate address to the regexp native functions

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index c7e81a95ffd12e26ce585c5f0dc64d446144164b..4fe6d4af9ca815023c77159b7a3a77bb50ccb2b0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1010,6 +1010,10 @@ class HeapObject: public Object {
   // The Heap the object was allocated in. Used also to access Isolate.
   // This method can not be used during GC, it ASSERTs this.
   inline Heap* GetHeap();
+  // Convenience method to get current isolate. This method can be
+  // accessed only when its result is the same as
+  // Isolate::Current(), it ASSERTs this. See also comment for GetHeap.
+  inline Isolate* GetIsolate();
 
   // Converts an address to a HeapObject pointer.
   static inline HeapObject* FromAddress(Address address);