In filters, use isArray instead of instanceof

[Ivshti]

Use the built-in isArray instead of "instanceof Array".
In the node-webkit framework, arrays may be created in the Node.js context, and for those arrays "instanceof Array" will return false, because the Array object of the browser context is a different reference. Using "Array.isArray" or the AngularJS function isArray fixes the problem.

[IgorMinar]

PR Checklist (Minor Bugfix)

• Contributor signed CLA now or in the past (if you just signed, leave a comment here with your real name)
• PR doesn't introduce new api
• PR doesn't contain a breaking change
• PR contains unit tests
• PR contains e2e tests (if suitable)
• PR contains documentation update (if suitable)
• PR passes all tests on Travis (sanity)
• PR passes all tests on ci.angularjs.org (cross-browser compatibility)
• PR is rebased against recent master
• PR is squashed into one commit per logical change
• PR's commit messages are descriptive and allows us to autogenerate release notes (required commit message format)
• All changes requested in review have been implemented

[IgorMinar]

Is there an easy way to create a browser based unit test for this? I can't think of any, so I'm ok with skipping unit tests for this one. please squash into a single commit, update commit message and sign CLA if you haven't yet.