Possibly duplicate dom_id when output is cached

Issue #1303880 included a fix that causes javascript settings to be keyed based off the dom_id. When caching is turned on, that dom_id is never updated. This causes issues when a views block is placed on a page after it has been cached when it's dom_id is taken by another block. We get duplicate settings in that key.

The settings for the duplicate key look like this:

"views_dom_id:7":{"view_name":["announcements","my_groups"],"view_display_id":["block_1","block_2"],"view_args":["",""],"view_path":["dashboard","dashboard"],"view_base_path":[null,null],"view_dom_id":[7,7],"pager_element":["0",0]}}}

instead of

"views_dom_id:7":{"view_name":"announcements","view_display_id":"block_1","view_args":"","view_path":"dashboard","view_base_path":null,"view_dom_id":7,"pager_element":"0"}

That will lead to ajax errors in ajax_view.js (line 61) that look like:
Uncaught TypeError: Object announcements,my_groups has no method 'replace'.

The JavaScript is expecting a string and gets an object instead.

My quick solution is to add a random number to the end of the key. With a high enough random number, collisions should be pretty low. There is probably a better solution out there though.

Patch will be included.