[debugger] Add test for Debug.scripts without listener.

test/mjsunit/debug-scripts-throw.js

Index: test/mjsunit/debug-scripts-throw.js
diff --git a/test/mjsunit/regress/regress-crbug-474297.js b/test/mjsunit/debug-scripts-throw.js
similarity index 53%
copy from test/mjsunit/regress/regress-crbug-474297.js
copy to test/mjsunit/debug-scripts-throw.js
index ce240251bdbc7abcab5be67742e14d9c920e8435..ee7cbd335b32cb6bb436da3bbbde36bebf65e700 100644
--- a/test/mjsunit/regress/regress-crbug-474297.js
+++ b/test/mjsunit/debug-scripts-throw.js
@@ -2,11 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --gc-interval=33 --expose-gc --allow-natives-syntax
+// Flags: --expose-debug-as debug
 
-var Debug = %GetDebugContext().Debug;
-Debug.setListener(function(){});
+// Get the Debug object exposed from the debug context global object.
+Debug = debug.Debug;
 
-%DebugGetLoadedScripts();
+assertThrows("Debug.scripts()");
+Debug.setListener(function(){});
 
+assertDoesNotThrow("Debug.scripts()");
 Debug.setListener(null);