fix(ngInclude): correctly add non-html namespaced template content

It is now possible for ngInclude to correctly load SVG content in non-blink
browsers, which do not sort out the namespace when parsing HTML.

/CC @tbosch / @IgorMinar

Closes #7538
originally I was trying it with Node.replaceChild() because I thought the compile nodes would still be children of the parent, but apparently that's not the case --- removing the for loop should be okay