Added missing event parameter for proxy function on the search form submit

[koenner01]

Description

When submitting the search form (mini) with an empty value, an error is throw on preventDefault

Fixed Issues (if relevant)

1. Submitting search form (mini) with empty value throws error on preventDefault #13791

Manual testing scenarios

1. See description and testing scenario in original issue Submitting search form (mini) with empty value throws error on preventDefault #13791

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @mzeis, thank you for the review.
MAGETWO-88331 has been created to process this Pull Request

[magento-engcom-team]

@koenner01 thank you for contributing. Please accept Community Contributors team invitation here to gain extended permissions for this repository.

[mzeis]

Hi @koenner01! Thank you very much for your contribution. Your PR fixes the issue for me.

[mzeis]

Hi @koenner01, thanks again for your PR! It has been merged into 2.2-develop.