Problem when I use the webdings font in firefox or inkscape

Question

I installed the webdings font in my computer, and it works well with LibreOffice.
But when I use the webdings font in a local html page : it doesn't work, the following unicode character is diplayed instead of the wanted character .
But if I export my local web page to PDF (with the wkhtmltopdf tool) I get the wanted character in the PDF.
So I don't understand why it doesn't work on my local web page (I tried with firefox and chromium). If someone has an idea?

I also tried in inkscape but I was unable to display my character in it.

A bit of code to clarify it :

/* the font in my css file */
@font-face {
    font-family:'webdings';
    font-weight: normal;
    font-style: normal;
    src: local('Webdings'), url('webdings.ttf') format('truetype'); }

.icone { font-family: webdings; }

<!-- my special character : it should be th earth -->
<td class="icone">&#xF0FC</td>