Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56010
Don't throw an IllegalArgumentException when JspFactory.getPageContext is used with JspWriter.DEFAULT_BUFFER
Based on a patch by Eugene Chung. (markt)

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1558811 13f79535-47bb-0310-9956-ffa450edef68