Allow apiInjectStylesheet to inject a URL

ext/bg/js/backend.js

@@ -499,19 +499,28 @@ class Backend {
         return Promise.resolve({frameId});
     }
 
-    _onApiInjectStylesheet({css}, sender) {
+    _onApiInjectStylesheet({type, value}, sender) {
         if (!sender.tab) {
             return Promise.reject(new Error('Invalid tab'));
         }
 
         const tabId = sender.tab.id;
         const frameId = sender.frameId;
-        const details = {
-            code: css,
+        const details = (
+            type === 'file' ?
+            {
+                file: value,
+                runAt: 'document_start',
+                cssOrigin: 'author',
+                allFrames: false
+            } :
+            {
+                code: value,
                 runAt: 'document_start',
                 cssOrigin: 'user',
                 allFrames: false
-        };
+            }
+        );
         if (typeof frameId === 'number') {
             details.frameId = frameId;
         }

ext/fg/js/popup.js

@@ -167,7 +167,7 @@ class Popup {
         } else {
             if (!css) { return; }
             try {
-                await apiInjectStylesheet(css);
+                await apiInjectStylesheet('code', css);
                 this._stylesheetInjectedViaApi = true;
             } catch (e) {
                 // NOP

ext/mixed/js/api.js

@@ -89,8 +89,8 @@ function apiFrameInformationGet() {
     return _apiInvoke('frameInformationGet');
 }
 
-function apiInjectStylesheet(css) {
-    return _apiInvoke('injectStylesheet', {css});
+function apiInjectStylesheet(type, value) {
+    return _apiInvoke('injectStylesheet', {type, value});
 }
 
 function apiGetEnvironmentInfo() {