[GN] Allow Xcode source indexing of non default files.

tools/gn/xcode_writer.cc

Index: tools/gn/xcode_writer.cc
diff --git a/tools/gn/xcode_writer.cc b/tools/gn/xcode_writer.cc
index 10624fa180d54a5d1df9067d8ca04ea720d5bb2d..e07633954df6142eb95e132207c16661d99b4623 100644
--- a/tools/gn/xcode_writer.cc
+++ b/tools/gn/xcode_writer.cc
@@ -325,9 +325,6 @@ void XcodeWriter::CreateSourcesProject(
     TargetOsType target_os) {
   std::vector<SourceFile> sources;
   for (const Target* target : targets) {
-    if (!target->settings()->is_default())
-      continue;
-
     for (const SourceFile& source : target->sources()) {
       if (source.is_system_absolute())
         continue;