Fix typo in int-to-double.md
Fix typo in int-to-double.md

Fixes #34449.

Bug: http://dartbug.com/34449
Change-Id: Ib2103e4340f7cc2267e71690ce0f7f60a7b453e4
Reviewed-on: https://dart-review.googlesource.com/74621
Reviewed-by: Erik Ernst <251bb01623bfda2cd9151e339a6e783ca432874c@google.com>
Commit-Queue: Lasse R.H. Nielsen <80295e4ef244a07779f93eaa95d582bad8e316a5@google.com>

dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk