Parsoid/Todo:Semantically insignificant whitespace round-tripping

Tracked in 39564

We need clean diffs, including semantically insignificant whitespace such as extra spaces between attributes in an HTML tag.

Possible solutions:


 * Tracking all semantically insignificant whitespace in rt information.
 * Advantage: works with any client
 * Disadvantage: a lot of work and rt info / code bloat; high cost/benefit
 * Selective serialization of modified DOM parts
 * Advantage: better cost/benefit ratio
 * Disadvantage: adds a burden on clients to mark modified parts of the DOM