containsSemanticBlockMarkup = function containsSemanticBlockMarkup(html, blockTags) {
	  return blockTags.some(function (tag) {
	    return html.indexOf('<' + tag) !== -1;
	  });
	}
Check to see if we have anything like <p> <blockquote> <h1>... to create
block tags from. If we do, we can use those and ignore <div> tags. If we
don't, we can treat <div> tags as meaningful (unstyled) blocks.