バリデートすると下記の注意が出るのですが、なぜ、トランスパイル後下記のように''がなくなってしまうのでしょうか？バグですか？

バリデートすると下記の注意が出るのですが、なぜ、トランスパイル後下記のように''がなくなってしまうのでしょうか？バグですか？
無視するしかないでしょうか？
.c-symbol:before{font-family:Mono Social Icons Font;-webkit-tex

エラー
空白文字を含むフォントファミリー名は引用符で囲む必要があります。引用符を省略した場合、名前の前後の空白文字は無視され、また名前の途中に含まれる連続した空白文字は全て一つの空白文字に変換されます



ここに言語を入力
/* * Web-Font "FontName" licensed under the SIL Open Font License * http://drinchev.github.io/monosocialiconsfont/ */
@font-face {
    font-family: 'Mono Social Icons Font';
    src: url('../web-font/MonoSocialIconsFont-1.10.eot');
    src: url('../web-font/MonoSocialIconsFont-1.10.eot?#iefix') format('embedded-opentype'),
         url('../web-font/MonoSocialIconsFont-1.10.woff') format('woff'),
         url('../web-font/MonoSocialIconsFont-1.10.ttf') format('truetype'),
         url('../web-font/MonoSocialIconsFont-1.10.svg#MonoSocialIconsFont') format('svg');/*unuse*/
    src: url('../web-font/MonoSocialIconsFont-1.10.ttf') format('truetype');
    font-weight: normal;
    font-style: normal;
}

・w3c上のコメント

@font-face {
{
font-family : Mono Social Icons Font;
src : url(../web-font/MonoSocialIconsFont-1.10.eot);
src : url(../web-font/MonoSocialIconsFont-1.10.eot?#iefix) format('embedded-opentype'), url(../web-font/MonoSocialIconsFont-1.10.woff) format('woff'), url(../web-font/MonoSocialIconsFont-1.10.ttf) format('truetype'), url(../web-font/MonoSocialIconsFont-1.10.svg#MonoSocialIconsFont) format('svg');
src : url(../web-font/MonoSocialIconsFont-1.10.ttf) format('truetype');
}

下記のようなエラーもでます。
おそらく自動にベンダープリフィックスをつけるからだと思います。
can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-ext-pseudo-class
1 can't find the warning message for deprecated
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-ext-pseudo-element
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension
1 can't find the warning message for vendor-extension