Signature plugin causes infinite $digest loop

[thomaspaulb]

Affected Angular versions: at least 1.5.7, 1.6.4

How to reproduce:

1. Download demo code
2. Add this snippet inside the main function in app.js:

    var nbDigest = 0;
    $rootScope.$watch(function() {
      nbDigest++;
      console.log('.');
    });

3. Observe digest getting called indefinitely.

This is a problem in complex applications with many different elements on the screen, since the whole lot of it gets reevaluated multiple times per second and crashes the browser.

[thomaspaulb]

Also found the culprit.