ESLint Config Migration: Fixing lint errors for "no-use-before-define" rule.

[filmaj]

Summary

This is a PR that should be merged into #1024 and incrementally addresses #842.

No ESLint config changes here - just getting the no-use-before-define rule passing.

Impact

Before

✖ 838 problems (649 errors, 189 warnings)
  111 errors and 0 warnings potentially fixable with the `--fix` option.

After

✖ 775 problems (586 errors, 189 warnings)
  109 errors and 0 warnings potentially fixable with the `--fix` option.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.