[Impeller] Fix variable name spelling/typos in several comments.

[timmaffett]

This is just a trivial PR that fixes several comments where the coord variable name is referenced as coods.

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
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• I listed at least one issue that this PR fixes in the description above.
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test-exempt. See [testing the engine] for instructions on writing and running engine tests.
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[bdero]

Thanks!

[auto-submit]

auto label is removed for flutter/engine, pr: 40909, due to This PR has not met approval requirements for merging. You have project association NONE and need 1 more review(s) in order to merge this PR.

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[auto-submit]

auto label is removed for flutter/engine, pr: 40909, due to Validations Fail.

[jonahwilliams]

LGTM

[auto-submit]

auto label is removed for flutter/engine, pr: 40909, due to - The status or check suite Mac Unopt has failed. Please fix the issues identified (or deflake) before re-applying this label.

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Changes reported for pull request #40909 at sha aa873a0