Bug fix : instanceOf returns false

[redoC-A2k]

Related Issues

fixes #1272

Description

I tried to debug the issue , while debuggging I found out that even though splide_list element containing HTMLElement in prototype chain the isHTMLElement was returning false . I compared the two window variables one was iframe and other should be global window , but in grapesjs case the two window variables were same and I think that's why instanceOf might be returning false . When I used window.top instead of window isntanceOf returns true as expected .

[TobiasRoos-Dev]

@NaotoshiFujita could you already review this pull request? I have a problem which this request would fix. I render for a cms splide in an iframe and this isn't possible for chrome browsers