net-libs/webkit-gtk: Remove security vulnerable SLOT=2 and SLOT=3

These slots are years old, unmaintained and vulnerable to hundreds of
bugs with a CVE assigned. Additionally there are some known unfixed
issues building against newer ICU. No interest in continued maintenance
of known hugely security vulnerable versions, thus with no consumers
remaining in main tree, this is going away now. Sorry.
If you need this, please think seriously ten times before you make it
available to yourself via an overlay, or use any software that requires
this security riddled version still.

Closes: https://bugs.gentoo.org/577068

net-libs/webkit-gtk/Manifest

@@ -1,2 +1 @@
 DIST webkitgtk-2.18.6.tar.xz 14829316 BLAKE2B 4c0140c17d513f064efe09aaefff434e3cbf2a88691c7916ed393bf9bd25a3cb5a1d4ea8699eb7e0d678d807293b66c4629e46df9088df9b4d122c554b280ead SHA512 375907d4c84e27aaa4b5df9a71424488c1b2ba0cf1d63e107d678c0f55f677996a80e9d9a9d4a412b40d1d0dde77b88464c54246cbafe70751042ec8a7bbe029
-DIST webkitgtk-2.4.11.tar.xz 9869100 BLAKE2B 9b1351976dc753025e6aba86a40f97fdf58821a6a7af109140a18adc7a0e1d8c140711b48bceeb3c4c189e7d52f258520623c7d971c46b6f2572c0e1de0d0100 SHA512 2e2cf01a52b8593765a0a3c2d7f0ad306121660019eb402226bd2826c7d4666dab4e91ca6ccbd29abe0ad3993549f256ed1ab88de22e9c8516d5f40a4edd6bfb

net-libs/webkit-gtk/metadata.xml

@@ -8,7 +8,6 @@
 <use>
 	<flag name="coverage">Enable code coverage support</flag>
 	<flag name="egl">Enable EGL support</flag>
-	<flag name="geoloc">Enable geolocation support through <pkg>app-misc/geoclue</pkg></flag>
 	<flag name="geolocation">Enable geolocation support through <pkg>app-misc/geoclue</pkg></flag>
 	<flag name="gles2">Enable GLESv2 support</flag>
 	<flag name="nsplugin">Enable full nsplugin support (GTK2 plugins)</flag>