add mark

packages/core/src/Mark.ts

@@ -0,0 +1,19 @@
+import Extension from './Extension'
+
+export default abstract class Mark extends Extension {
+
+  constructor(options = {}) {
+    super(options)
+  }
+
+  public type = 'mark'
+
+  schema(): any {
+    return null
+  }
+
+  get schemaType() {
+    return this.editor.schema.marks[this.name]
+  }
+
+}