Add "purpose" argument to getSubmission.
https://bugzilla.mozilla.org/show_bug.cgi?id=587780
Interrupt ContextSearch.search() for safe when nsISearchEngine.getSubmission() returns null.
Unindent block.
Support Firefox Health Report.
https://bugzilla.mozilla.org/show_bug.cgi?id=840177

I thought that it's no problem that this addon supports Firefox Health
report.
Update min. support version.