Fixes #4150: adding programmatically created layout widgets to existing (and started) layout widgets broken.
Fixes #4150: adding programmatically created layout widgets to
existing (and started) layout widgets broken.

Call child.startup() in addChild(), if child isn't already started.

Child.startup() needs to be called after child is connected
to the dom tree (in particular, layout widgets need to
query to see if their parent is a layout widget),
but before parent.addChild() calls child.resize()... so it really
needs to happen in the middle of parent.addChild().

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@10245 560b804f-0ae3-0310-86f3-f6aa0a117693

Sam-Cummins/delite,harbalk/delite,kitsonk/delite,Sam-Cummins/delite,kitsonk/delite,harbalk/delite