Fix 2440

[lukeapage]

Don't do weird pulling apart of rules and rulesets, just bubble imports and charsets.

I think the code was left over from when we didn't bubble rulesets out of the nesting before calling toCSS

@seven-phases-max would you review? It looks and feels safe to me. Your example output

.a {
  @charset "utf-8";
  @import "test.csS";
}

is unchanged before and after

[lukeapage]

okay I'll just merge this then

[seven-phases-max]

Oh, sorry, I simply missed you asked me to review (probably it came surrounded with a couple of other new issues/PRs and I simply skipped a few incl. this one, just aways trusting your PRs as being safe unless the stuff they fix/change is too weird itself).

Now by looking at the code I realize we missed one thing in #2440. According to http://www.w3.org/TR/css3-syntax/#charset-rule @charset probably must go before comments i.e. charset > comments (if any) > imports. Though I can't find if they explicitly state that charset detection stage takes place before comments elimination but I guess it does (obviously comments have to be parsed according to the same encoding option).

[lukeapage]

Yes, the code should do that - it inserts at charsetNodeIndex which is only incremented by other charset nodes...