Fix loading of fonts with invalid encoding name entry (bug 859204 and 878112)
Terminate worker of previous doc
Merge pull request #4153 from sriram-dev/4027-destroy-previous-doc

4027 - Terminate worker of previous doc
Merge pull request #4147 from Snuffleupagus/bug-859204

Fix loading of fonts with invalid encoding name entry (bug 859204 and 878112)