fix(ngHref): allow setting href to empty string

[nickeddy]

Fixed issue 2755:
#2755

ngHref should now allow empty strings, and ngSrc will not accept empty strings as intended: b6e4a71

[caitp]

You need a test, it should be easy to write:

  it('should remove href value when interpolated value is empty', inject(function($compile, $rootScope) {
    element = $compile('<div ng-href="{{id}}"></div>')($rootScope)
    $rootScope.$digest();
    expect(element.attr('href')).toEqual('');

    $rootScope.$apply(function() {
      $rootScope.id = 1;
    });
    expect(element.attr('href')).toEqual('1');
  }));

Or something (I don't know if that test will pass yet, but the interpolated value won't be empty if you put ng-href="someString{{interpolated}}", because the interpolated value is always the concatenation of the raw string stuff and the expression's toString()'d value

[shahata]

This is is breaking the current behavior of not setting the href attribute when the value is empty. It will result in href="" which will point to the current base href. Also the test doesn't make sense since it tests transition from empty to not empty and not vice versa. Also 2, I thought it was clear that I started working on this PR. Uncool. :(

[caitp]

hmm, @shahata has a point. Maybe removing the attribute entirely would make more sense

[chrisirhc]

+1 Just ran into this. Unable to disable a link without another directive that does preventDefault.

[shahata]

This is solved more thoroughly by #6986

[caitp]

@shahata your CL is bitrotten because of matsko's change to attrs, needs a rebase. Also, I suggest not calling the scope "booleanAttrs", it's specific to ngHref, imo

[btford]

Superseded by 469ea33. Thanks though, @nickeddy!