Split ActivityLogging attributes in IDLExtendedAttributes.
The new format is:
LogActivity=|GetterOnly|SetterOnly
LogAllWorlds

LogActivity defaults to logging both Getter and Setter, or Method, as
appropriate.
LogAllWorlds, if present, means that logging will occur in both isolated worlds
and the main world. If absent, logging will occur only in isolated worlds.

Split off from https://codereview.chromium.org/213783002/

BUG=366167

Review URL: https://codereview.chromium.org/249833002

git-svn-id: svn://svn.chromium.org/blink/trunk@172452 bbb929c8-8fbe-4397-9dbb-9b2b20218538