dillon1000/react

Expose the rendered children before they're actually mounted

Exposing the _renderedChildren property before all the children are fully
mounted. This allows us to debug a partially mounted tree when the debugger
has a breakpoint in the one of the mounting children.

This only has a functional difference in the case where mounting throws. This
will end up not mounting the component anyway. Any remounting shouldn't be
affected by this change.