IDOM renders children with extra spaces preceding and following child elements

This is because there are extra spaces around this element definition on the client:

https://github.com/idom-team/idom/blob/fe56b77ee19da5cdbadc5e7f5f42e35fa84bdc90/idom/client/app/core_modules/layout.js#L117

This isn't an issue except when the HTML is placed in a `<pre/>` tag since then all the extra spaces have meaning.