Introduce some Uint8Array.prototype.toBase64 usage in the main code…

…-base

See https://github.com/tc39/proposal-arraybuffer-base64

src/display/font_loader.js

@@ -15,7 +15,6 @@
 
 import {
   assert,
-  bytesToString,
   FeatureTest,
   isNodeJS,
   shadow,
@@ -409,9 +408,8 @@ class FontFaceObject {
     if (!this.data || this.disableFontFace) {
       return null;
     }
-    const data = bytesToString(this.data);
     // Add the @font-face rule to the document.
-    const url = `url(data:${this.mimetype};base64,${btoa(data)});`;
+    const url = `url(data:${this.mimetype};base64,${this.data.toBase64()});`;
     let rule;
     if (!this.cssFontInfo) {
       rule = `@font-face {font-family:"${this.loadedName}";src:${url}}`;