This gives us a means of using JS objects returned by UserContentManager
script messages directly from Vala.
* bindings/metadata/WebKit2-4.0.metadata: Tweak standard webkit2 VAPI to
re-include methods that return javascriptcore objects.
* bindings/vapi/javascriptcore-4.0.vapi: Copy generated VAPI file into
the tree, customise it so that it actually works.
* src/CMakeLists.txt: Generate the custom webkit2 VAPI, depend on
javascriptcore and include in-tree javascriptcore VAPI in the client
build.
* bindings/metadata/JSCore-3.0.metadata: Remove obsolete file.
