Revert 'auto-magic' "\begin{foo}*" <=> "\begin{foo*}" mapping

This change was added in SVN3684, but the team as a whole are unsure that
it is the correct approach to deal with this issue. As such, further
discussion is needed before any public release of such a change.

Note that SVN3684 also included a change in the end-of-group code
for environments in IniTeX mode. This is left in place here, as it is
required irrespective of the handling of *-environments.

l3packages/xparse/xparse.dtx

@@ -1082,21 +1082,9 @@
     \cs_generate_from_arg_count:cNnn
       { environment_ #1 _end_aux:w } \cs_set_protected:Npn
       \l_@@_current_arg_int {#4}
-%    \end{macrocode}
-%   When working with \LaTeXe{} the environment begin/end functions have to
-%   have \enquote{exposed} names. There is also a check to see if the very
-%   first argument is a star: if so, this is \enquote{shuffled} so that a 
-%   definition |\DeclareDocumentEnvironent { foo } { s } ... | will work
-%   as expected.  
-%    \begin{macrocode}
 %<*package>
     \cs_set_eq:cc {#1}       { environment~ #1 }
     \cs_set_eq:cc { end #1 } { environment~ #1 ~end }
-    \tl_if_head_eq_charcode:nNT {#2} s
-      {
-        \cs_set_protected:cpx { #1 * } { \exp_not:c { environment~ #1 } * }
-        \cs_set_eq:cc { end #1 * } { environment~ #1 ~end }
-      }
 %</package>
   }
 %    \end{macrocode}

news/SVN-snapshot-July-2012.txt

@@ -140,11 +140,5 @@ The snapshot includes the usual list of more general changes in l3kernel:
  - Bug in expandable functions fixed so that they will
    correctly accept \par tokens is the argument signature is
    appropriate.
- - Enable xparse-defined environments to treat starred version
-   as a parameter so that
-
-     \DeclareDocumentEnvironment{foo}{s}{...}{...}
-
-   will correctly work with "\begin{foo*}" or "\begin{foo}*".
  - Revise definition of 'NoValue' such that it does not use a
    document-level token at all.