1. grid.base.js line 860

I'm using HTML5 page.

tagName in all web browsers are in capital characters with content_type = 'text/html'. But tagName in all web browsers are in lower case with content_type = 'application/xhtml+xml'. Better to make code independed of content_type.

Also you can make

if(this.tagName.toUpperCase()!='TABLE')

2. yes