jslint content.js: add use strict and indent all file

This breaks tests since it hides all functions in a closure. A fix will
follow.
Fix tests: expose worker functions

The many changes in tests.js all add a 'nlp.' and nothing more.
jslint content.js: fixup variable declarations
jslint content.js: avoid assignment in loop condition
jslint content.js: add missing radix parameters
jslint content.js: fix function order

Only call functions that are already declared in the file.
Remove dead code
jslint content.js: stub out undefined chrome stuff
jslint content.js: start linting the file