Text::recalcTextStyle should reattach text when a parent gets white-space: pre

If the parent of an whitespace text node gets white-space: pre (or other sigificant
whitespace values) and the text node does not already have a renderer we need to
reattach it so that we get a renderer.

R=ojan@chromium.org,eseidel@chromium.org
BUG=231749

Review URL: https://chromiumcodereview.appspot.com/18967011

git-svn-id: svn://svn.chromium.org/blink/trunk@154168 bbb929c8-8fbe-4397-9dbb-9b2b20218538