Bug 1359541 - Enable eslint on mobile/android/tests; r=standard8,snorp

.eslintignore

mobile/android/tests/.eslintrc

mobile/android/tests/browser/chrome/.eslintrc.js

mobile/android/tests/browser/chrome/head.js

mobile/android/tests/browser/chrome/test_home_provider.html

.../android/tests/browser/chrome/test_session_form_data.html

mobile/android/tests/browser/chrome/test_web_channel.html

mobile/android/tests/browser/robocop/robocop_input.html

mobile/android/tests/browser/robocop/testFilePicker.js

mobile/android/tests/browser/robocop/testReadingListCache.js