Check obj exists before attempting to perform "querySelectorAll"

fixes: Uncaught TypeError: Cannot read property 'querySelectorAll' of undefined
when mail widget is used on dashboard and a user isn't logged in
Better fix
Removed tests.js references in manifests for Chrome, Opera, and FF.
changed body to #header for overflow-x: hidden to fix issue with scrolling screen
Merge pull request #831 from brettp/no_tests

Removed tests.js references in manifests for Chrome, Opera, and FF.
Clean up utils.js to avoid variable issues
Update Flickr expando regex; fixes #825
Disable NER on wiki pages; fixes #848
Merge pull request #858 from mc10/never-ending-reddit

Disable NER on wiki pages
Delete unused Firefox README files
Copyedit and update documentation
Use ndashes for file lists
Rework title and introduction
Copyedit and fix typos
Avoid using a "here" link
Fix Firefox instructions
Remove unneeded double ``
Merge pull request #859 from mc10/readme

Copyedit and update README
firefox survives saving data if store.json isn't created yet

e.g. first install, launching with fresh profile
technically it recovers from an exception loading the file, which hopefully won't lead to *more* data loss
@honestbleeps @SirCmpwn attn
Update user tagger to enable a "show anyway" option on ignored posts