Prevent clicks from being called on disabled buttons (hack for angular bug)

[melcher]

There's a bug/feature in angular where calling .click() or .trigger('click') on a disabled button, which would normally do nothing in a regular browser/html situation, actually propagates the click event through the stack. This means that, in our testing, clicking "Save" on a disabled save button will totally do the save action. Who knew?
Seems like behave could step in here and not click on a disabled button/link (or maybe error?). The reproducible fiddle for angular is here:

http://jsfiddle.net/e78xjvLu/3/ (angular 1.2.28). This does not appear to be an issue in 1.21

[melcher]

Filed at angular/angular#451