Fix setPreferences regression from the e10s patch (PR 5115)
Add back pdfBugEnabled pref check in the |log| function in extensions/firefox/content/PdfStreamConverter.jsm
Update the license header in extensions/firefox/content/pdfjschildbootstrap.js; see https://bugzilla.mozilla.org/show_bug.cgi?id=942707#c99
Rename |_isPrefAllowed| to |_ensurePreferenceAllowed| in extensions/firefox/content/PdfjsChromeUtils.jsm
Merge pull request #5305 from Snuffleupagus/e10s-fixes

Miscellaneous e10s fixes