Make `gn refs` look at script files.

tools/gn/command_refs.cc

Index: tools/gn/command_refs.cc
diff --git a/tools/gn/command_refs.cc b/tools/gn/command_refs.cc
index 014d7e8996dc08ec62b598a99fc06b3141a081cc..fcd824a6842ea72bef034ec308055d02d8a17664 100644
--- a/tools/gn/command_refs.cc
+++ b/tools/gn/command_refs.cc
@@ -145,6 +145,9 @@ bool TargetContainsFile(const Target* target, const SourceFile& file) {
       return true;
   }
 
+  if (target->action_values().script().value() == file.value())
+    return true;
+
   std::vector<SourceFile> outputs;
   target->action_values().GetOutputsAsSourceFiles(target, &outputs);
   for (const auto& cur_file : outputs) {