Restore IsolateData destructor

runtime/bin/isolate_data.h

Index: runtime/bin/isolate_data.h
diff --git a/runtime/bin/isolate_data.h b/runtime/bin/isolate_data.h
index 29d2884714b6557eae579934634b4bbc7ce83ed6..fae210489182f1544f52b17e476dc11562fc84f0 100644
--- a/runtime/bin/isolate_data.h
+++ b/runtime/bin/isolate_data.h
@@ -21,9 +21,9 @@ class EventHandler;
 // when the isolate shuts down.
 class IsolateData {
  public:
-  explicit IsolateData(const char* url,
-                       const char* package_root,
-                       const char* packages_file)
+  IsolateData(const char* url,
+              const char* package_root,
+              const char* packages_file)
       : script_url(strdup(url)),
         package_root(NULL),
         packages_file(NULL),
@@ -36,14 +36,13 @@ class IsolateData {
       this->packages_file = strdup(packages_file);
     }
   }
-#if 0
+
   ~IsolateData() {
     free(script_url);
     free(package_root);
     free(packages_file);
     free(udp_receive_buffer);
   }
-#endif
 
   char* script_url;
   char* package_root;