blink_gc_plugin: detect singletons with embedded ScriptWrappables.

tools/clang/blink_gc_plugin/Config.cpp

Index: tools/clang/blink_gc_plugin/Config.cpp
diff --git a/tools/clang/blink_gc_plugin/Config.cpp b/tools/clang/blink_gc_plugin/Config.cpp
index fa00782cc6b79f2c81d15840f1ea24ef36aebca6..1ec3c78d12c48c5496bc6601346116d92a9237fe 100644
--- a/tools/clang/blink_gc_plugin/Config.cpp
+++ b/tools/clang/blink_gc_plugin/Config.cpp
@@ -49,6 +49,18 @@ void Config::UseLegacyNames() {
   kIsHeapObjectAliveName = legacy::kIsHeapObjectAliveName;
 }
 
+bool Config::IsAnnotated(clang::Decl* decl, const std::string& anno) {
+  if (!decl->hasAttrs())
+    return false;
+
+  for (const clang::Attr* attr : decl->getAttrs()) {
+    const clang::AnnotateAttr* annotation = dyn_cast<clang::AnnotateAttr>(attr);
+    if (annotation && annotation->getAnnotation() == anno)
+      return true;
+  }
+  return false;
+}
+
 bool Config::IsTemplateInstantiation(CXXRecordDecl* record) {
   ClassTemplateSpecializationDecl* spec =
       dyn_cast<clang::ClassTemplateSpecializationDecl>(record);