fix extension manager

docs/src/demos/Extensions/Bold/index.vue

@@ -30,10 +30,10 @@ export default {
   mounted() {
     this.editor = new Editor({
       extensions: [
-        new Document(),
-        new Paragraph(),
-        new Text(),
-        new Bold(),
+        Document(),
+        Paragraph(),
+        Text(),
+        Bold(),
       ],
       content: `
         <p>This isn’t bold.</p>

docs/src/demos/Extensions/Code/index.vue

@@ -30,10 +30,10 @@ export default {
   mounted() {
     this.editor = new Editor({
       extensions: [
-        new Document(),
-        new Paragraph(),
-        new Text(),
-        new Code(),
+        Document(),
+        Paragraph(),
+        Text(),
+        Code(),
       ],
       content: `
         <p>This isn’t code.</p>

docs/src/demos/Extensions/History/index.vue

@@ -33,10 +33,10 @@ export default {
   mounted() {
     this.editor = new Editor({
       extensions: [
-        new Document(),
-        new Paragraph(),
-        new Text(),
-        new History(),
+        Document(),
+        Paragraph(),
+        Text(),
+        History(),
       ],
       content: `
         <p>Edit this text and press undo to test this extension.</p>

docs/src/demos/Extensions/Italic/index.vue

@@ -30,10 +30,10 @@ export default {
   mounted() {
     this.editor = new Editor({
       extensions: [
-        new Document(),
-        new Paragraph(),
-        new Text(),
-        new Italic(),
+        Document(),
+        Paragraph(),
+        Text(),
+        Italic(),
       ],
       content: `
         <p>This isn’t italic.</p>