module:re: Fixed bug where IndexError was not thrown on invalid str groupname
module:re: Fixed bug where IndexError was not thrown on invalid str groupname

This commit fixes a short coming in the indexing operator on js objects
so that we can avoid operator overloading in this module. This commit
checks to see if a particular string group name exists and throws an
IndexError per the python spec if it does not exist

QQuick/Transcrypt,QQuick/Transcrypt,QQuick/Transcrypt,QQuick/Transcrypt,QQuick/Transcrypt