Don't use updateStyleForNodeIfNeeded in ApplyBlockElementCommand::rangeForParagraphSplittingTextNodesIfNeeded

It's not correct to use updateStyleForNodeIfNeeded in this method because it's going
to return a raw pointer to a RenderStyle and a later call could cause a style recalc
which would free this style (and might also change the style of this node).

Instead we should call updateStyleIfNeeded() before the calls to this method.

BUG=285787

Review URL: https://chromiumcodereview.appspot.com/23561004

git-svn-id: svn://svn.chromium.org/blink/trunk@157337 bbb929c8-8fbe-4397-9dbb-9b2b20218538