Fix for...of autocomplete, variable declaration

[fd-rey]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions

Description of the Change

Following the for...of reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of

The variable declaration with "var" is missing and the autogenerated snippet produces a ReferenceError
if the variable used in the for is not declared previously in the code.

Alternate Designs

Benefits

The forof autocomplete snippet can be used safely.

Possible Drawbacks

If the user wants to use an already declared variable, the declaration with "var" in the for has to be removed manually.

Applicable Issues

#596

[jasonrudolph]

Thanks, @fd-rey. ⚡