IDL compiler: finish [PutForwards]

* [PerWorldBindings, PutForwards]
* [PutForwards] with extended attributes on the target attribute

Remaining: 3 => 2

BUG=239771
R=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/156233003

git-svn-id: svn://svn.chromium.org/blink/trunk@166568 bbb929c8-8fbe-4397-9dbb-9b2b20218538