Support typed children in TSX

[agubler]

@matt-gadd commented on Wed Sep 13 2017

Enhancement

TypeScript now supports typed children in TSX, we need to update our JSX namespace to leverage it by adding the ElementChildrenAttribute.

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@matt-gadd commented on Tue Jun 05 2018

Okay this doesn't currently work due to ElementChildrenAttribute looking on the ElementAttributesProperty, which in our case is properties. See microsoft/TypeScript#18357