uiGridConstants.filter.CONTAINS not working for date filters

[JayHuang]

Filing a new issue as closed PRs don't give notifications.

This is a reference to this PR: #2772

The following code:

    if (filter.flags.date === true) {
      value = new Date(value);
      // If the term has a dash in it, it comes through as '\-' -- we need to take out the '\'.
      term = new Date(term.replace(/\\/g, ''));
    }

only executes if condition is not uiGridConstants.filter.STARTS_WITH, ENDS_WITH, CONTAINS, or EXACT.

However, in the case of a user typing dates into a column filter, it's very common for them to type a partial match of the date. Date comparisons only being restricted to GREATER_THAN, GREATER_THAN_OR_EQUAL, LESS_THAN, LESS_THAN_OR_EQUAL is not sufficient.

[PaulL1]

I'm not sure how we'd do a partial match of a date object. I think you're imagining someone could type "5 June" and it'd find "5 June 2014" and "5 June 2015". But in reality "5 June" can't be converted to a date (it has no year), and with any i18n running we don't want to do this comparison by taking apart the string and trying to work out what days or months they put in. So in this case, doing a string match is actually the best answer for any kind of contains query.