[infra] Translate _sources.gypi files to _sources.gni files

sdk/lib/convert/convert_sources.gni

Index: sdk/lib/convert/convert_sources.gni
diff --git a/sdk/lib/convert/convert_sources.gni b/sdk/lib/convert/convert_sources.gni
new file mode 100644
index 0000000000000000000000000000000000000000..ad7964978e6ea998aa5cf4f9b4b71931443a374e
--- /dev/null
+++ b/sdk/lib/convert/convert_sources.gni
@@ -0,0 +1,23 @@
+# Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+# This file contains all sources for the dart:convert library.
+convert_sdk_sources = [
+  "convert.dart",
+
+  # The above file needs to be first as it lists the parts below.
+  "ascii.dart",
+  "base64.dart",
+  "byte_conversion.dart",
+  "chunked_conversion.dart",
+  "codec.dart",
+  "converter.dart",
+  "encoding.dart",
+  "html_escape.dart",
+  "json.dart",
+  "latin1.dart",
+  "line_splitter.dart",
+  "string_conversion.dart",
+  "utf.dart",
+]