[iOS][gn] Port blink_html_tokenizer to build with gn.

ios/third_party/blink/BUILD.gn

Index: ios/third_party/blink/BUILD.gn
diff --git a/ios/third_party/blink/BUILD.gn b/ios/third_party/blink/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..83e0e7a9c31e07285ee710037cbad371e0e0400a
--- /dev/null
+++ b/ios/third_party/blink/BUILD.gn
@@ -0,0 +1,20 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+source_set("html_tokenizer") {
+  deps = [
+    "//base",
+  ]
+
+  sources = [
+    "src/html_character_provider.h",
+    "src/html_input_stream_preprocessor.h",
+    "src/html_markup_tokenizer_inlines.h",
+    "src/html_token.h",
+    "src/html_token.mm",
+    "src/html_tokenizer.h",
+    "src/html_tokenizer.mm",
+    "src/html_tokenizer_adapter.h",
+  ]
+}