Fix ftbfs

v8/include/cppgc/visitor.h:440:19: error: invalid application of 'sizeof' to an incomplete type 'blink::CSSStyleSheet'
  440 |     static_assert(sizeof(T), "Pointee type must be fully defined.");

diff -up chromium-141.0.7390.37/third_party/blink/renderer/bindings/scripts/bind_gen/observable_array.py.ftbfs-csss_style_sheet chromium-141.0.7390.37/third_party/blink/renderer/bindings/scripts/bind_gen/observable_array.py
--- chromium-141.0.7390.37/third_party/blink/renderer/bindings/scripts/bind_gen/observable_array.py.ftbfs-csss_style_sheet	2025-09-23 22:21:14.000000000 +0200
+++ chromium-141.0.7390.37/third_party/blink/renderer/bindings/scripts/bind_gen/observable_array.py	2025-10-01 17:55:51.303926035 +0200
@@ -433,6 +433,7 @@ def generate_observable_array(observable
     header_node.accumulator.add_include_headers([
         component_export_header(api_component, for_testing),
         "third_party/blink/renderer/bindings/core/v8/idl_types.h",
+        "third_party/blink/renderer/core/css/css_style_sheet.h",
         "third_party/blink/renderer/platform/bindings/observable_array.h",
     ])
     source_node.accumulator.add_include_headers([