[bootstrapper] extra natives must not use natives syntax.

test/mjsunit/debug-script.js

Index: test/mjsunit/debug-script.js
diff --git a/test/mjsunit/debug-script.js b/test/mjsunit/debug-script.js
index 8874960208240389e77d269af0c4f7a7b7e40f26..df91ed5c45bfd505aaab7f6872b2ddb2c6c41baf 100644
--- a/test/mjsunit/debug-script.js
+++ b/test/mjsunit/debug-script.js
@@ -73,8 +73,8 @@ for (i = 0; i < scripts.length; i++) {
 
 // This has to be updated if the number of native scripts change.
 assertEquals(%NativeScriptsCount(), named_native_count);
-// Only the 'gc' extension is loaded.
-assertEquals(1, extension_count);
+// The 'gc' extension and one extras script is loaded.
+assertEquals(2, extension_count);
 // This script and mjsunit.js has been loaded.  If using d8, d8 loads
 // a normal script during startup too.
 assertTrue(normal_count == 2 || normal_count == 3);