try installing from full code if 'sections' is empty in style json

fixes #414

background/background.js

@@ -4,6 +4,7 @@ global handleCssTransitionBug detectSloppyRegexps
 global openEditor
 global styleViaAPI
 global loadScript
+global usercss
 */
 'use strict';
 
@@ -17,6 +18,9 @@ window.API_METHODS = Object.assign(window.API_METHODS || {}, {
     delete msg.method;
     return download(msg.url, msg);
   },
+  parseCss({code}) {
+    return usercss.invokeWorker({action: 'parse', code});
+  },
   getPrefs:    () => prefs.getAll(),
   healthCheck: () => dbExec().then(() => true),
 

content/install-hook-userstyles.js

@@ -241,6 +241,21 @@
 
   function getStyleJson() {
     return getResource(getStyleURL(), {responseType: 'json'})
+      .then(style => {
+        if (!style || !Array.isArray(style.sections) || style.sections.length) {
+          return style;
+        }
+        const codeElement = document.getElementById('stylish-code');
+        if (codeElement && !codeElement.textContent.trim()) {
+          return style;
+        }
+        return getResource(getMeta('stylish-update-url')).then(code => new Promise(resolve => {
+          chrome.runtime.sendMessage({method: 'parseCss', code}, ({sections}) => {
+            style.sections = sections;
+            resolve(style);
+          });
+        }));
+      })
       .catch(() => null);
   }
 

js/usercss.js

@@ -617,5 +617,5 @@ var usercss = (() => {
     });
   }
 
-  return {buildMeta, buildCode, assignVars};
+  return {buildMeta, buildCode, assignVars, invokeWorker};
 })();