Minor code clarity fixes

* Initialize for-loop variables as numbers rather than lists.
* Remove an unnecessary condition in the `@if` statement.
Fix whitespace collapse in Chrome 25

Work around a recent change to Chrome that results in the previous
whitespace collapsing technique failing. Chrome doesn't need the
`word-spacing` hack but it has started to respect the property, and
this is causing grid cells to overlap.

However, Opera for Windows does need the `word-spacing` hack. The
fix is to use an Opera prefixed pseudo-class in a new selector block for
the `word-spacing` declaration. All other supported browsers will ignore
the rule. Only the Android 4.2 browser still seems to have problems
fully collapsing the whitespace.
Update CHANGELOG
v0.2.2