Revert "Move dart:web to pkg:htmlescape."

runtime/bin/web_sources.gypi

Index: runtime/bin/web_sources.gypi
diff --git a/lib/math/math_sources.gypi b/runtime/bin/web_sources.gypi
similarity index 72%
copy from lib/math/math_sources.gypi
copy to runtime/bin/web_sources.gypi
index dc854da684570c574174c89c14463dd9f2901df2..e9a063d4bc657d82f245ce46ec4258ed1ba53ce4 100644
--- a/lib/math/math_sources.gypi
+++ b/runtime/bin/web_sources.gypi
@@ -2,9 +2,9 @@
 # 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:web library.
 {
   'sources': [
-    'base.dart',
-    'random.dart',
+    '../../lib/web/web.dart',
   ],
 }