diff --git a/bindings/metadata/WebKit2WebExtension-4.0-custom.vala b/bindings/metadata/WebKit2WebExtension-4.0-custom.vala
new file mode 100644
index 00000000..a994a774
--- /dev/null
+++ b/bindings/metadata/WebKit2WebExtension-4.0-custom.vala
@@ -0,0 +1,5 @@
+namespace WebKit {
+	namespace DOM {
+		public delegate void EventTargetFunc (WebKit.DOM.EventTarget target, WebKit.DOM.Event event);
+	}
+}
diff --git a/bindings/metadata/WebKit2WebExtension-4.0.metadata b/bindings/metadata/WebKit2WebExtension-4.0.metadata
new file mode 100644
index 00000000..c496dba4
--- /dev/null
+++ b/bindings/metadata/WebKit2WebExtension-4.0.metadata
@@ -0,0 +1,9 @@
+DOM* parent="WebKit.DOM" name="DOM(.+)"
+
+DOMEventTarget.add_event_listener skip
+_ContextMenu skip
+_ContextMenuItem skip
+
+Frame.get_javascript_* nullable=false unowned=true
+
+DOMEventTarget.add_event_listener_with_closure.handler type="owned WebKit.DOM.EventTargetFunc"
diff --git a/bindings/vapi/javascriptcore-4.0.vapi b/bindings/vapi/javascriptcore-4.0.vapi
index fd64630d..027d781b 100644
--- a/bindings/vapi/javascriptcore-4.0.vapi
+++ b/bindings/vapi/javascriptcore-4.0.vapi
@@ -5,18 +5,69 @@ namespace JS {
 
 	[CCode (cname = "JSGlobalContextRef")]
     [SimpleType]
-	public struct GlobalContext {
+	public struct GlobalContext : Context {
+
+        [CCode (cname = "JSValueIsBoolean")]
+        public bool is_boolean(JS.Value value);
 
         [CCode (cname = "JSValueIsNumber")]
         public bool is_number(JS.Value value);
 
+        [CCode (cname = "JSValueToBoolean")]
+        public bool to_boolean(JS.Value value);
+
         [CCode (cname = "JSValueToNumber")]
         public double to_number(JS.Value value, out JS.Value exception);
 
+        [CCode (cname = "JSGlobalContextRelease")]
+        public bool release();
+	}
+
+	[CCode (cname = "JSContextRef")]
+    [SimpleType]
+	public struct Context {
+
+        [CCode (cname = "JSEvaluateScript")]
+        public Value evaluate_script(String script,
+                                     Object? thisObject,
+                                     String? sourceURL,
+                                     int startingLineNumber,
+                                     out Value? exception);
+
+        [CCode (cname = "JSObjectMakeFunction")]
+        public Object make_function(String? name,
+                                    [CCode (array_length_pos=1.5)]
+                                    String[]? parameterNames,
+                                    String body,
+                                    String? sourceURL,
+                                    int startingLineNumber,
+                                    out Value? exception);
+
+        [CCode (cname = "JSObjectCallAsFunction")]
+        public Value call_as_function(Object object,
+                                      Object? thisObject,
+                                      [CCode (array_length_pos=2.5)]
+                                      Value[]? arguments,
+                                      out Value? exception);
+
+	}
+
+	[CCode (cname = "JSObjectRef")]
+    [SimpleType]
+	public struct Object {
 	}
 
 	[CCode (cname = "JSValueRef")]
     [SimpleType]
 	public struct Value {
 	}
+
+	[CCode (cname = "JSStringRef", ref_function = "JSStringRetain", unref_function = "JSStringRelease")]
+    [SimpleType]
+	public struct String {
+
+        [CCode (cname = "JSStringCreateWithUTF8CString")]
+        public String.create_with_utf8_cstring(string str);
+        
+	}
 }
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 2b11bf98..46c23b39 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -544,10 +544,13 @@ set(CLIENT_PACKAGES
   ${EXTRA_CLIENT_PACKAGES}
 )
 
+# webkit2gtk-web-extension-4.0 is included as custom VAPI below
 set(WEB_PROCESS_PACKAGES
   geary-engine
   gee-0.8
   gtk+-3.0
+  javascriptcore-4.0
+  libsoup-2.4
   webkit2gtk-web-extension-4.0
 )
 
@@ -641,7 +644,9 @@ target_link_libraries(geary-engine m ${DEPS_LIBRARIES} sqlite3-unicodesn)
 # WebKit2GTK VAPI generation
 #################################################
 add_custom_target(webkit2gtk-vapi
-  DEPENDS "${CMAKE_BINARY_DIR}/src/webkit2gtk-4.0.vapi"
+  DEPENDS
+    "${CMAKE_BINARY_DIR}/src/webkit2gtk-4.0.vapi"
+    "${CMAKE_BINARY_DIR}/src/webkit2gtk-web-extension-4.0.vapi"
 )
 add_custom_command(
     OUTPUT
@@ -654,6 +659,18 @@ add_custom_command(
     COMMAND
         vapigen --library=webkit2gtk-4.0 --pkg gtk+-3.0 --pkg libsoup-2.4 --pkg javascriptcore-4.0 --vapidir=${CMAKE_SOURCE_DIR}/bindings/vapi --metadatadir=${CMAKE_SOURCE_DIR}/bindings/metadata --directory=${CMAKE_BINARY_DIR}/src `${PKG_CONFIG_EXECUTABLE} --variable=girdir gobject-introspection-1.0`/WebKit2-4.0.gir
 )
+add_custom_command(
+    OUTPUT
+        "${CMAKE_BINARY_DIR}/src/webkit2gtk-web-extension-4.0.vapi"
+    DEPENDS
+        "${CMAKE_SOURCE_DIR}/bindings/metadata/WebKit2WebExtension-4.0.metadata"
+        "${CMAKE_SOURCE_DIR}/bindings/metadata/WebKit2WebExtension-4.0-custom.vala"
+        "${CMAKE_SOURCE_DIR}/bindings/vapi/javascriptcore-4.0.vapi"
+    WORKING_DIRECTORY
+        "${CMAKE_SOURCE_DIR}/bindings/metadata"
+    COMMAND
+        vapigen --library=webkit2gtk-web-extension-4.0 --pkg gtk+-3.0 --pkg libsoup-2.4 --pkg javascriptcore-4.0 --vapidir=${CMAKE_SOURCE_DIR}/bindings/vapi --metadatadir=${CMAKE_SOURCE_DIR}/bindings/metadata --directory=${CMAKE_BINARY_DIR}/src `${PKG_CONFIG_EXECUTABLE} --variable=girdir gobject-introspection-1.0`/WebKit2WebExtension-4.0.gir WebKit2WebExtension-4.0-custom.vala
+)
 
 # Client library (static lib used for building client and unit tests)
 #################################################