Skip http_proxy_test and secure_builtin_roots_test.

tests/standalone/standalone.status

 # Copyright (c) 2013, 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.
 
 # WARNING:
 # Tests using the multitest feature where failure is expected should *also* be
 # listed in tests/lib/analyzer/analyze_tests.status without the "standalone"
 # prefix.
 
 package/invalid_uri_test: Fail, OK # CompileTimeErrors intentionally
@@ skipping 31 matching lines @@
 # checked mode with no benefit. Skip.
 io/file_fuzz_test: Skip
 io/directory_fuzz_test: Skip
 
 [ ($runtime == vm || $runtime == dart_precompiled) && $system == macos ]
 # This test fails with "Too many open files" on the Mac OS buildbot.
 # This is expected as MacOS by default runs with a very low number
 # of allowed open files ('ulimit -n' says something like 256).
 io/socket_many_connections_test: Skip
 
+[ $runtime == vm && $system == linux ]
+# These tests have started timing out and issue 25649 has been filed to
+# investigate, skipping these tests temporarily to get the bots to be
+# green again.
+io/http_proxy_test: Skip
+io/secure_builtin_roots_test: Skip
+
+
 [ ($compiler == none || $compiler == precompiler) && ($runtime == drt || $runtime == dartium || $runtime == ContentShellOnAndroid) ]
 typed_array_test: RuntimeError, OK  # Uses Isolate.spawn
 typed_array_int64_uint64_test: RuntimeError, OK  # Uses Isolate.spawn
 typed_data_isolate_test: SkipByDesign # This test uses dart:io
 io/*: SkipByDesign # Don't run tests using dart:io in the browser
 package/*: Skip # Do not run those in Dartium.
 full_coverage_test: Skip
 http_launch_test: Skip
 vmservice/*: SkipByDesign # Do not run standalone vm service tests in browser.
 issue14236_test: Skip # Issue 14236 Script snapshots do not work in the browser.
@@ skipping 203 matching lines @@
 io/test_runner_test: RuntimeError # Platform.executable
 io/file_lock_test: RuntimeError # Platform.executable
 io/code_collection_test: RuntimeError # Platform.executable
 io/file_lock_test: RuntimeError # Platform.executable
 io/code_collection_test: RuntimeError # Platform.executable
 io/raw_socket_cross_process_test: RuntimeError # Platform.executable
 io/test_extension_test: RuntimeError # Platform.executable
 io/regress_7679_test: RuntimeError # Platform.executable
 
 io/process_*: Skip # Most use Platform.executable