lg-keyword(): Sass 3.2 vs. Sass 3.3

lg-keyword_3.2.scss

@mixin lg-keyword($keyword, $colorstops...) {
    $prefixes: '-webkit-';
    
    // 標準のキーワード
    $standard_keywords:
        to bottom, to left, to top, to right,
        to top left, to top right, to bottom right, to bottom left,
        to left top, to right top, to right bottom, to left bottom;
        
    // 接頭辞版のキーワード
    $legacy_keywords:
        top, right, bottom, left,
        bottom right, bottom left, top left, top right,
        right bottom, left bottom, left top, right top;
    
    // キーワードのインデックスを取得
    $idx: index($standard_keywords, $keyword);
    
    // キーワードが不正な場合は何も出さない
    @if $idx {
        // マッチする接頭辞版のキーワードを取得
        $legacy_keyword: nth($legacy_keywords, $idx);
        
        @each $prefix in $prefixes {
            background-image: #{$prefix}linear-gradient($legacy_keyword, $colorstops);
        }
        background-image: linear-gradient($keyword, $colorstops);
    }
}

lg-keyword_3.3.scss

@mixin lg-keyword($keyword, $colorstops...) {
    $prefixes: '-webkit-';

    $keywords_map: (
        to bottom:       top,
        to left:         right,
        to top:          bottom,
        to right:        left,
        to top left:     bottom right,
        to top right:    bottom left,
        to bottom right: top left,
        to bottom left:  top right,
        to left top:     right bottom,
        to right top:    left bottom,
        to right bottom: left top,
        to left bottom:  right top
        );
    
    // キーワードが不正な場合は何も出さない
    @if map-has-key($keywords_map, $keyword) {        
        @each $prefix in $prefixes {
            background-image: #{$prefix}linear-gradient(map-get($keywords_map, $keyword), $colorstops);
        }
        background-image: linear-gradient($keyword, $colorstops);
    }
}