dom: Adds compile-time size checker to Node.

As same as CSSValue, this patch adds a compile-time size checker to Node.

BUG=235436

Review URL: https://codereview.chromium.org/380113002

git-svn-id: svn://svn.chromium.org/blink/trunk@177810 bbb929c8-8fbe-4397-9dbb-9b2b20218538