Remove checkout of NSS and sqlite from DEPS, remove support files.

runtime/bin/zlib.gyp

 # Copyright (c) 2012 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.
 
 # Copyright (c) 2012, 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 is a modified copy of src/third_party/zlib/zlib.gyp from Chromium.
-# Revision 291806 (this should agree with "nss_rev" in DEPS).
+# This file is a modified copy of
+# https://chromium.googlesource.com/chromium/src/third_party/zlib/zlib.gyp
+# at revision c3d0a6190f2f8c924a05ab6cc97b8f975bddd33f.
 {
   # Added by Dart. All Dart comments refer to the following block or line.
   'includes': [
-    '../../tools/gyp/runtime-configurations.gypi',
-    '../../tools/gyp/nss_configurations.gypi',
+    '../tools/gyp/runtime-configurations.gypi',
+    '../tools/gyp/nss_configurations.gypi',
   ],
   'variables': {
     # Added by Dart.
-    'zlib_path': '../../../third_party/zlib',
+    'zlib_path': '../../third_party/zlib',
   },
   # Added by Dart.  We do not indent, so diffs with the original are clearer.
   'conditions': [[ 'dart_io_support==1', {
   'targets': [
     {
       'target_name': 'zlib_dart',  # Added by Dart (the _dart postfix)
       'type': 'static_library',
       # Added by Dart (the original only has this on android).
       'toolsets':['host','target'],
       # Changed by Dart: '<(zlib_directory)/' added to all paths.
@@ skipping 36 matching lines @@
       },
       'conditions': [
         ['OS!="win"', {
           'product_name': 'chrome_zlib',
         }],
       ],
     },
   ],
   }]],
 }