dillon1000/react

[Fiber] Fix rendering SVG into non-React SVG tree (#8638)

* Add a test for rendering SVG into a non-React SVG tree

It is failing in Fiber.

* Add a test for rendering HTML into non-React foreignObject

It happens to pass in Fiber.

* Determine root namespace by container namespace, not just tag

A tag alone is not enough to determine the tree namespace.

* Skip the test that exhibits jsdom bug in non-createElement mode

jsdom doesn't give HTML namespace to foreignObject.innerHTML children.
This problem doesn't exist in the browsers.

https://github.com/facebook/react/pull/8638#issuecomment-269349642

We will skip this test in non-createElement mode considering
that non-createElement mounting is effectively dead code now anyway.