Could not load file or assembly 'WebGrease, Version=1.5.1.25624, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

answer worked :  http://stackoverflow.com/questions/19851912/could-not-load-file-or-assembly-webgrease-version-1-5-1-25624-culture-neutral