Remove unused optional parameters of private functions.

[srawlins]

Description

Remove unused optional parameters of private functions.

This is required to enable checking for unused optional parameters of private
functions. dart-lang/sdk#29731

Related Issues

Tests

I added no tests.

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[Piinks]

Hey @srawlins! it looks like the analyzer is unhappy here, can you take a look? :)

[srawlins]

I pushed a commit, and I think analyze-linux is now failing on some unrelated thing.

[Piinks]

I pushed a commit, and I think analyze-linux is now failing on some unrelated thing.

Right you are. The issues with url_launcher in the analyzer failure was a break on master yesterday. They have been resolved now, so updating with the latest from master should clear it up. :)

[srawlins]

I think good to go!

[Piinks]

LGTM!