Meta: Port recent changes to GN build

80071b1d48face038a60b98fc8c3414de1cb9633
3f6a26d07d1536eb5e4e39eedfd4e0135eabf536

Meta/gn/secondary/Userland/Libraries/LibJS/BUILD.gn

@@ -16,6 +16,7 @@ shared_library("LibJS") {
     "//Userland/Libraries/LibLocale",
     "//Userland/Libraries/LibRegex",
     "//Userland/Libraries/LibSyntax",
+    "//Userland/Libraries/LibTimeZone",
     "//Userland/Libraries/LibUnicode",
   ]
   if (current_cpu == "x86" || current_cpu == "x64") {

Meta/gn/secondary/Userland/Libraries/LibTimeZone/BUILD.gn

@@ -69,6 +69,8 @@ source_set("LibTimeZone") {
     "$target_gen_dir/..",
   ]
   sources = [
+    "DateTime.cpp",
+    "DateTime.h",
     "Forward.h",
     "TimeZone.cpp",
     "TimeZone.h",