re #1801: Reimplement enable_http_compression to replace skin script.

Actually, it might be possible to delete the enable_compression method
entirely, it doesn't seem to be used by Plone. I'm just not sure whether
3rd-party code might rely on it even though I think it's unlikely.

CHANGES.rst

@@ -13,6 +13,9 @@ New features:
 - Add test for Revert to Revision action in History Viewlet
   [davilima6]
 
+- Reimplement enable_http_compression to replace skin script. #1801
+  [tlotze]
+
 Bug fixes:
 
 - Show document byline for logged-in users. Fixes #160

plone/app/layout/viewlets/httpheaders.py

@@ -24,7 +24,7 @@ class HTTPCachingHeaders(HeaderViewlet):
 
     def enable_compression(self):
         """Call to activate gzip"""
-        self.context.enableHTTPCompression(request=self.request, enable=1)
+        self.request.RESPONSE.enableHTTPCompression(REQUEST=self.request)
 
     def getHeaders(self):
         lang = getattr(self.context, 'Language', None)