Handle missing 'FontName' entry in FontDescriptor object
Merge pull request #2566 from mduan/issue2099

Handle missing 'FontName' entry in FontDescriptor object
Skip commands that have too few arguments

- Commands that have too few args will be skipped
- Commands that have too many args will generate an info, but still
execute
Merge pull request #2549 from mduan/issue2391

Skip commands that have too few arguments
Merge branch 'master' of https://github.com/mozilla/pdf.js

Conflicts:
	test/pdfs/.gitignore
	test/test_manifest.json