Stop waiting for non scratch fonts to load.

src/lib/font-loader-hoc.jsx

@@ -4,6 +4,17 @@ import omit from 'lodash.omit';
 import {connect} from 'react-redux';
 import {setFontsLoaded} from '../reducers/fonts-loaded';
 
+// This list is from scratch-render-fonts:
+// https://github.com/LLK/scratch-render-fonts/blob/master/src/index.js#L4
+const FONTS = [
+    'Sans Serif',
+    'Serif',
+    'Handwriting',
+    'Marker',
+    'Curly',
+    'Pixel',
+    'Scratch'
+];
 /* Higher Order Component to provide behavior for loading fonts.
  * @param {React.Component} WrappedComponent component to receive fontsLoaded prop
  * @returns {React.Component} component with font loading behavior
@@ -22,8 +33,12 @@ const FontLoaderHOC = function (WrappedComponent) {
                     typeof document.fonts.values === 'function' &&
                     typeof document.fonts.values()[Symbol.iterator] === 'function') {
                     for (const fontFace of document.fonts.values()) {
-                        fontPromises.push(fontFace.loaded);
-                        fontFace.load();
+                        // Only load fonts from this list. If we load all fonts on the document, we may block on
+                        // loading fonts from things like chrome extensions.
+                        if (FONTS.indexOf(fontFace.family) !== -1) {
+                            fontPromises.push(fontFace.loaded);
+                            fontFace.load();
+                        }
                     }
                 }
                 return fontPromises;