Preserve node type when breaking text nodes.
Preserve node type when breaking text nodes.

michael/substance-1,podviaznikov/substance,jacwright/substance,jacwright/substance,abhaga/substance,andene/substance,podviaznikov/substance,TypesetIO/substance,abhaga/substance,stencila/substance,michael/substance-1,substance/substance,TypesetIO/substance,substance/substance,andene/substance