Update to Chromium revision 176706.
- See crbug.com/167209 for a description of why NSPrincipalClass needs to be specified in helper-Info.plist.

git-svn-id: http://chromiumembedded.googlecode.com/svn/trunk/cef3@987 5089003a-bbd8-11dd-ad1f-f1f9622dbc98