Simplify.
There is no real need to convert every attribute name into numeric tag via lookup table, when there are only two attribute names that we recognize.

In the old code there was an average of (ATTRIBUTE_NAMES.length/2) = 11 String.equals() calls when looking up a numeric 'tag'.
In the new code there will be two String.equals() calls.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1624586 13f79535-47bb-0310-9956-ffa450edef68