flatten method
Replace the rule set that contains nested rules with the flatten rule sets.
Implementation
void flatten(StyleSheet styleSheet) {
// TODO(terry): Iterate over topLevels instead of _expansions it's already
// a map (this maybe quadratic).
_expansions.forEach((RuleSet ruleSet, List<RuleSet> newRules) {
var index = styleSheet.topLevels.indexOf(ruleSet);
if (index == -1) {
// Check any @media directives for nested rules and replace them.
var found = _MediaRulesReplacer.replace(styleSheet, ruleSet, newRules);
assert(found);
} else {
styleSheet.topLevels.insertAll(index + 1, newRules);
}
});
_expansions.clear();
}