WinScope: Modify instead of replacing proto objects

Converting the proto object inorder to set the enum string values
or display default values replaces existing proto objects and its
properties which maybe used by the formatter function.

Instead replace toObject method with a custom one that limits
modifications to the existing proto objects.

Test: run WinScope and check WM and SF traces

Change-Id: Ie084d288aaf569476f1e9284c3a9c8a06364a61a