Updates to the coding style document.
Updates to the coding style document.

The changes reflect what we have learned and converged to since we
last reviewed the document. There is nothing fundamentally new.

scala-js/scala-js,gzm0/scala-js,sjrd/scala-js,gzm0/scala-js,scala-js/scala-js,scala-js/scala-js,sjrd/scala-js,sjrd/scala-js