add deleteSelection command

packages/core/src/commands/deleteSelection.ts

@@ -0,0 +1,15 @@
+import { Editor } from '../Editor'
+import { deleteSelection } from 'prosemirror-commands'
+
+type DeleteSelection = () => any
+
+declare module '../Editor' {
+  interface Editor {
+    deleteSelection: DeleteSelection,
+  }
+}
+
+export default (next: Function, { state, view }: Editor): DeleteSelection => () => {
+  deleteSelection(state, view.dispatch)
+  next()
+}