[inspector] Refactor protocol-test.js

test/inspector/debugger/stepping-after-get-possible-breakpoints.js

Index: test/inspector/debugger/stepping-after-get-possible-breakpoints.js
diff --git a/test/inspector/debugger/stepping-after-get-possible-breakpoints.js b/test/inspector/debugger/stepping-after-get-possible-breakpoints.js
index 7d6577b82ac105d3048310980c23db41ca8bb300..c36a36cb071055bc9a7a3587dcbc1f5f2d830a3d 100644
--- a/test/inspector/debugger/stepping-after-get-possible-breakpoints.js
+++ b/test/inspector/debugger/stepping-after-get-possible-breakpoints.js
@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-InspectorTest.addScript(`
+let {session, contextGroup, Protocol} = InspectorTest.start('Tests that stepping works after calling getPossibleBreakpoints');
+
+contextGroup.addScript(`
 function boo() {}
 boo();
 function foo() {}