Fixed Chrome Invidious CSS issues.

Apparently the chrome API doesn't work well with CSS.

Resolves https://github.com/ajayyy/SponsorBlock/issues/241

src/utils.ts

@@ -6,6 +6,17 @@ class Utils {
     // Contains functions needed from the background script
     backgroundScriptContainer: any = null;
 
+    // Used to add content scripts and CSS required
+    js = [
+        "./js/vendor.js",
+        "./js/content.js"
+    ];
+    css = [
+        "content.css",
+        "./libs/Source+Sans+Pro.css",
+        "popup.css"
+    ];
+
     constructor(backgroundScriptContainer?: any) {
         this.backgroundScriptContainer = backgroundScriptContainer;
     }
@@ -67,25 +78,15 @@ class Utils {
      * For now, it is just SB.config.invidiousInstances.
      */
     setupExtraSiteContentScripts() {
-        let js = [
-            "./js/vendor.js",
-            "./js/content.js"
-        ];
-        let css = [
-            "content.css",
-            "./libs/Source+Sans+Pro.css",
-            "popup.css"
-        ];
-
         let self = this;
 
         if (this.isFirefox()) {
             let firefoxJS = [];
-            for (const file of js) {
+            for (const file of this.js) {
                 firefoxJS.push({file});
             }
             let firefoxCSS = [];
-            for (const file of css) {
+            for (const file of this.css) {
                 firefoxCSS.push({file});
             }
 
@@ -119,8 +120,8 @@ class Utils {
                     // This API is experimental and not visible by the TypeScript compiler
                     actions: [new (<any> chrome.declarativeContent).RequestContentScript({
                         allFrames: true,
-                        js,
-                        css
+                        js: self.js,
+                        css: self.css
                     })]
                 };