Meta: Port ad440f9e9ac6c9692cd7f61e06d2dab2a5d0c80c to gn build

Meta/gn/secondary/Ladybird/WebContent/BUILD.gn

@@ -1,5 +1,6 @@
 import("//Ladybird/link_qt.gni")
 import("//Ladybird/moc_qt_objects.gni")
+import("//Meta/gn/build/libs/pulse/enable.gni")
 
 moc_qt_objects("generate_moc") {
   sources = [
@@ -30,6 +31,7 @@ executable("WebContent") {
   deps = [
     ":generate_moc",
     "//AK",
+    "//Meta/gn/build/libs/pulse",
     "//Userland/Libraries/LibCore",
     "//Userland/Libraries/LibFileSystem",
     "//Userland/Libraries/LibGfx",

Meta/gn/secondary/Userland/Libraries/LibWeb/Platform/BUILD.gn

@@ -3,6 +3,7 @@ source_set("Platform") {
   deps = [ "//Userland/Libraries/LibWeb:all_generated" ]
   sources = [
     "AudioCodecPlugin.cpp",
+    "AudioCodecPluginAgnostic.cpp",
     "EventLoopPlugin.cpp",
     "EventLoopPluginSerenity.cpp",
     "FontPlugin.cpp",