Errors while rendering templates no longer log the generated code.

Now that stack traces have source line info, the full code is hopefully
unnecessary (and if it is needed, this isn't the best way to get it).
Syntax errors in the generated code will still dump the whole thing
to the log.

tornado/template.py

@@ -257,12 +257,7 @@ def generate(self, **kwargs):
         # we've generated a new template (mainly for this module's
         # unittests, where different tests reuse the same name).
         linecache.clearcache()
-        try:
-            return execute()
-        except Exception:
-            formatted_code = _format_code(self.code).rstrip()
-            app_log.error("%s code:\n%s", self.name, formatted_code)
-            raise
+        return execute()
 
     def _generate_python(self, loader, compress_whitespace):
         buffer = cStringIO.StringIO()