[stdlib] Remove unnecessary declaration

[LiamSwayne]

i was an unnecessary and unclear declaration that could be substituted for end. This is not a behavioral change.

Reasoning:

• i was set to be equivalent to end, but was never used in a way in which it could not simply be substituted for end.
• i is not descriptive, and end does a better job describing it's purpose. i didn't have a comment either, also making it less descriptive than end.
• var i was used almost immediately after a different i was used as a counter in a for loop, and it could be confusing to use two variables with different purposes and the same name immediately after one another.
• Removing this declaration could result in a small performance improvement because an assignment is removed, but at the very least the code is simpler without this declaration.