Error checking for length parameter of external array constructors in shell

src/d8.h

Index: src/d8.h
diff --git a/src/d8.h b/src/d8.h
index f3760e8bc8ed37f8b7a81db557276bf131bf805c..e22546999325a34a52aa002c05e473a852e5f100 100644
--- a/src/d8.h
+++ b/src/d8.h
@@ -217,7 +217,7 @@ class Shell: public i::AllStatic {
   static Counter* GetCounter(const char* name, bool is_histogram);
   static Handle<Value> CreateExternalArray(const Arguments& args,
                                            ExternalArrayType type,
-                                           int element_size);
+                                           size_t element_size);
   static void ExternalArrayWeakCallback(Persistent<Value> object, void* data);
 };