Get rid of all component builds specific .isolate.

build/linux/system.isolate

Index: build/linux/system.isolate
diff --git a/build/linux/system.isolate b/build/linux/system.isolate
deleted file mode 100644
index 3933af1e2ee9a0c0069775e6536cfdb2d7817b1b..0000000000000000000000000000000000000000
--- a/build/linux/system.isolate
+++ /dev/null
@@ -1,12 +0,0 @@
-# Copyright 2014 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.
-{
-  # This file is only used with the condition "desktop_linux==1 or chromeos==1".
-  'includes': [
-    # This is only used when use_openssl==0.
-    # TODO(rsleevi): This is awkward, because this file is imported from
-    # base.isolate but references net, causing an improper import cycle.
-    '../../net/third_party/nss/ssl.isolate',
-  ],
-}