[Optimisation] Don't add whitespace nodes to elements

[jacobp100]

When compiling, I see a lot of appendNode( createText( "\n " ), tbody$1 );. On some elements, like pre, this is important. On others, like trs, it's not. It would be great if we could add an optimisation to omit whitespace nodes.

[jacobp100]

Just a quick experiment reduced my app from 3.89KB (min+gz) to 3.73KB—that's about 5%!

[Rich-Harris]

Agree — there are definitely some cases where this could be done better. Unfortunately there are others that are less clear-cut — for example, whitespace between elements becomes significant if those elements have a display: inline-block style. (In those cases, the whitespace could be collapsed down to a single character, and thus a shared helper function which would compress better, but then you have to hope that they're not white-space: pre for some reason.) There's no way to know at compile time which styles will apply, so you could easily break people's expectations if you were too aggressive. It could be an option though.

I'm going to close this as there's already a discussion underway at #189.