perf(ngOptions): prevent initial options repaiting

[pbr1111]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Bug fix.

What is the current behavior? (You can also link to an open issue here)
Refers to this issue: ngOptions slow performance in IE due to option rerendering

What is the new behavior (if this is a feature change)?
Now the options are loaded once when we create the <select ng-options> directive. Also, if we add an <option> element with an ng-if directive, it is not deleted now.

Does this PR introduce a breaking change?
No.

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:
None.

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[pbr1111]

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