[GTK] Add a GKeyFile especialization to GOwnPtr

[GTK] Add a GKeyFile especialization to GOwnPtr
https://bugs.webkit.org/show_bug.cgi?id=77191

Reviewed by Martin Robinson.

Source/JavaScriptCore:

* wtf/gobject/GOwnPtr.cpp:
(WTF::GKeyFile): Implement freeOwnedGPtr for GKeyFile.
* wtf/gobject/GOwnPtr.h: Add GKeyFile template.
* wtf/gobject/GTypedefs.h: Add forward declaration for GKeyFile.

Source/WebKit2:

* Shared/gtk/ArgumentCodersGtk.cpp:
(CoreIPC::decodeGKeyFile): Use GOwnPtr for GKeyFile.
(CoreIPC::encode): Ditto.
(CoreIPC::decode): Ditto.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@106117 268f45cc-cd09-0410-ab3c-d52691b4dbfc