Fix($animate) : svg element with classNameFilter animation fix.

[sreeramu]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
classNameFilter for animation with svg element should work same as the other elements.

What is the current behavior? (You can also link to an open issue here)
classNameFilter not working for svg element.

What is the new behavior (if this is a feature change)?
classNameFilter also handles svg element.

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:
This PR fix #14508 issue.

Fix($animate) : svg element with classNameFilter animation fix.

[Narretz]

Looks good. I only wonder if getAttribute is much slower than className.

[sreeramu]

@Narretz can we do like this?
angular.isString(node.className) ? node.className : node.getAttribute('class')

[jbedard]

I don't think it's worth the isString check. jQuery recently switched from className to get/setAttribute and actually reported it being faster: jquery/jquery#2268