Add libart to basebrowser lists so that someone else doesn't spend 2 hrs wondering why the embedding tests don't work when you happen to have svg enabled.

embedding/config/basebrowser-unix

@@ -118,6 +118,7 @@ components/libjsurl.so
 components/jsurl.xpt
 
 ; layout
+libmoz_art_lgpl.so
 components/libgkcontent.so
 res/dtd/*
 components/libgklayout.so                   

embedding/config/basebrowser-win

@@ -126,6 +126,7 @@ components\jsurl.dll
 components\jsurl.xpt
 
 ; layout
+moz_art_lgpl.dll
 components\gkcontent.dll
 res\dtd\*
 components\gklayout.dll