public XMLWriter escapedAsciiContent(String content,boolean multiline) {
        closeStartTag();
        if (content==null) return this;
        if (multiline) currentIsMultiline=true;
        return w(content);
    }
Writes the given US-ASCII only string as-is.
If the content is <b>not</b> US-ASCII <i>only</i> this <i>may</i> cause
incorrectly encoded content to be written.
This is faster than using escapedContent as transcoding is skipped.
<p>
The content string <i>must</i> be XML escaped before calling this.
If the content is null this does nothing but closing the start tag.

@param content the content - output by XML.xmlEscape(content.toString())
@param multiline whether the content should be treated as multiline,
       such that the following end tag should appear on a new line
vespajlib/src/main/java/com/yahoo/text/XMLWriter.java