fix(core): isNodeSelection, isTextSelection not always false (#3089)

Fixes #2979.  Since the ProseMirror TypeScript upgrade, these have
always returned false, since the Selection type tree are all classes
now.

packages/core/src/helpers/isNodeSelection.ts

@@ -1,7 +1,5 @@
 import { NodeSelection } from 'prosemirror-state'
 
-import { isObject } from '../utilities/isObject'
-
 export function isNodeSelection(value: unknown): value is NodeSelection {
-  return isObject(value) && value instanceof NodeSelection
+  return value instanceof NodeSelection
 }

packages/core/src/helpers/isTextSelection.ts

@@ -1,7 +1,5 @@
 import { TextSelection } from 'prosemirror-state'
 
-import { isObject } from '../utilities/isObject'
-
 export function isTextSelection(value: unknown): value is TextSelection {
-  return isObject(value) && value instanceof TextSelection
+  return value instanceof TextSelection
 }

packages/core/src/utilities/isClass.ts

@@ -1,7 +0,0 @@
-export function isClass(value: any): boolean {
-  if (value.constructor?.toString().substring(0, 5) !== 'class') {
-    return false
-  }
-
-  return true
-}

packages/core/src/utilities/isObject.ts

@@ -1,10 +0,0 @@
-import { isClass } from './isClass'
-
-export function isObject(value: any): boolean {
-  return (
-    value
-    && typeof value === 'object'
-    && !Array.isArray(value)
-    && !isClass(value)
-  )
-}