refactor(ivy): remove superfluous Array check

[benlesh]

related #25755

Simply removes an unnecessary Array.isArray check that was left in from a previous change.

[ngbot]

I see that you just added the PR action: merge label, but the following checks are still failing:
     missing required status "code-review/pullapprove"
     status "continuous-integration/travis-ci/pr" is pending
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[benlesh]

g3sync presubmit here: https://test.corp.google.com/ui#id=OCL:212293425:BASE:212293494:1536601600323:6dfab9fb

[mary-poppins]

You can preview a6c3a92 at https://pr25894-a6c3a92.ngbuilds.io/.

[angular-automatic-lock-bot]

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