Move getFaviconClass out of render and simplify

While I'm not sure if this is faster than three nested .some calls,
it shouldn't be a lot slower and I'd say it makes the code at least somewhat
more clear.

This does no longer prioritize blog over review, but that probably doesn't
matter since I'm not sure those can exist at the same time for the same
entity type and even if they could, something being a blog and review
for the same entity at the same time would just be bad data, so it's irrelevant
which icon it shows.

root/static/scripts/edit/externalLinks.js

@@ -145,6 +145,42 @@ type LinksEditorState = {
   +links: $ReadOnlyArray<LinkStateT>,
 };
 
+function getFaviconClass(
+  relationships: $ReadOnlyArray<LinkRelationshipT>,
+  url: string,
+) {
+  let faviconClass = '';
+
+  for (const relationship of relationships) {
+    const linkType = relationship.type
+      ? linkedEntities.link_type[relationship.type]
+      : null;
+
+    if (linkType) {
+      // If we find a homepage, that's the icon we want and we're done
+      if (/^official (?:homepage|site)$/.test(linkType.name)) {
+        return 'home';
+      } else if (linkType.name === 'blog') {
+        faviconClass = 'blog';
+      } else if (linkType.name === 'review') {
+        faviconClass = 'review';
+      }
+    }
+  }
+
+  if (nonEmpty(faviconClass)) {
+    return faviconClass;
+  }
+
+  for (const key of Object.keys(FAVICON_CLASSES)) {
+    if (url.indexOf(key) > 0) {
+      return FAVICON_CLASSES[key];
+    }
+  }
+
+  return 'no';
+}
+
 export class _ExternalLinksEditor
   extends React.Component<LinksEditorProps, LinksEditorState> {
   creditableEntityProp: 'entity0_credit' | 'entity1_credit' | null;
@@ -1428,57 +1464,9 @@ export class ExternalLink extends React.Component<LinkProps> {
     });
     const firstLink = props.relationships[0];
 
-    let faviconClass: string | void;
-    if (notEmpty) {
-      const isHomepage = props.relationships.some(link => {
-        const linkType = link.type
-          ? linkedEntities.link_type[link.type]
-          : null;
-        if (linkType) {
-          return /^official (?:homepage|site)$/.test(linkType.name);
-        }
-        return false;
-      });
-      if (isHomepage) {
-        faviconClass = 'home';
-      } else {
-        const isBlog = props.relationships.some(link => {
-          const linkType = link.type
-            ? linkedEntities.link_type[link.type]
-            : null;
-          if (linkType) {
-            return /^blog$/.test(linkType.name);
-          }
-          return false;
-        });
-        if (isBlog) {
-          faviconClass = 'blog';
-        } else {
-          const isReview = props.relationships.some(link => {
-            const linkType = link.type
-              ? linkedEntities.link_type[link.type]
-              : null;
-            if (linkType) {
-              return /^review$/.test(linkType.name);
-            }
-            return false;
-          });
-          if (isReview) {
-            faviconClass = 'review';
-          } else {
-            for (const key of Object.keys(FAVICON_CLASSES)) {
-              if (props.url.indexOf(key) > 0) {
-                faviconClass = FAVICON_CLASSES[key];
-                break;
-              }
-            }
-            if (!faviconClass) {
-              faviconClass = 'no';
-            }
-          }
-        }
-      }
-    }
+    const faviconClass = notEmpty
+      ? getFaviconClass(props.relationships, props.url)
+      : null;
 
     return (
       <>