Bug 28910: Correct eslint errors in OPAC basket.js

Bug 28910: Correct eslint errors in OPAC basket.js

This patch corrects eslint errors in the OPAC copy of basket.js:
Indentation inconsistencies, undeclared variables, unused functions,
etc.

To test, apply the patch and test the "Cart" functionality in the
OPAC:

- In the OPAC, add an item to the cart.
- A popup message should appear telling you the item has been added.
- The "Add to cart" link should update to read "In your cart."
- The count if cart items in the header should be updated.
- The "In your cart (remove)" link should work correctly.
- Test this process from both the search results and
  detail pages.
- Open the cart.
- The cart should open correctly.
- In the cart, test all the controls:
  - More details
  - Send
  - Download
  - Empty and close
  - Hide window
  - Print
  - Select all / clear all
  - With checked items:
    - Remove
    - Add to list
    - Place hold
    - Tag

The following unused functions were removed: readCookieValue,
AllAreChecked, SelectAll, and quit. A search of the Koha codebase should
return no results from the opac-tmpl directory.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>