fix(ngOptionsDirective): fix form pristine (use !equals function instead of !== for issue 13211)

[m-amr]

This pull request is related to Issue

#13211

it solves form $pristine and $dirty wrong values in case of multi select element

prevoiusValue and nextValue are array for example

previousValue = [1,2]
nextValue = [1,2]

The are the same value but the === operator will return false because they are array
after some debugging i found that these lines cause the problem

if (!ngModelCtrl.$isEmpty(previousValue)) {
      var nextValue = selectCtrl.readValue();
      if (ngOptions.trackBy ? !equals(previousValue, nextValue) : previousValue !== nextValue) {
        ngModelCtrl.$setViewValue(nextValue);
        ngModelCtrl.$render();
      }
    }

what cause the problem is ngOptions.trackBy is undefined and
(previousValue !== nextValue) i will be true becuase [1,2] !== [1,2]

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[m-amr]

I signed it!

[Narretz]

Thanks for the PR.I think we are very specifically only using equals with track by because of performance issues. But I think this is the right place to fix it. We should probably use equals also if the select is multiple.

[m-amr]

@Narretz
Thanks for your feedback
I understand that angular is not always use equals function to compare the values
due to performance issue

i improved my solution
now we should use equals function to compare values
in case of ngOptions.trackBy or select is multiple (values are not primitive)
else we use equal operator to compare values (values are Primitive)

i added these lines to fix the problem

var isNotPrimitive = ngOptions.trackBy || multiple;
if (isNotPrimitive ? !equals(previousValue, nextValue) : previousValue !== nextValue) {
     ngModelCtrl.$setViewValue(nextValue);
     ngModelCtrl.$render();
 }

I think this fix the problem and won't cause performance Issue in case of select is a single value.

[Narretz]

Looks good. I'll merge it tomorrow.