WebRTC: Update Macs to 10.10 (with Xcode 7)

masters/master.tryserver.webrtc/slaves.cfg

 # 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.
 
 slaves = [
   # Linux.
   {
     'master': 'WebRTCTryServer',
     'os': 'linux',
     'version': 'precise',
@@ skipping 77 matching lines @@
     'builder': [
       'linux_baremetal',
     ],
     'hostname': 'build22-a4',
   }
 ] + [
   # Mac.
   {
     'master': 'WebRTCTryServer',
     'os': 'mac',
-    'version': '10.8',
+    'version': '10.10',
     'bits': '64',
     'builder': [
       'mac_asan',
       'mac_compile_dbg',
       'mac_compile_rel',
       'mac_compile_x64_dbg',
       'mac_compile_x64_rel',
       'mac_dbg',
       'mac_rel',
       'mac_swarming',
       'mac_x64_dbg',
       'mac_x64_gn_dbg',
       'mac_x64_gn_rel',
       'mac_x64_rel',
       'ios_dbg',
       'ios_rel',
       'ios_arm64_dbg',
       'ios_arm64_rel',
       'ios32_sim_dbg',
       'ios64_sim_dbg',
       'ios64_gn_dbg',
       'ios64_gn_rel',
     ],
     'hostname': 'vm%d-m4' % i,
   } for i in range(510, 513) + range(665, 667) + range(738, 741) +
-             range(818, 820) + [748]
+             range(818, 820) + [748, 1033]
 ] + [
+  # Mac bare-metal machines with audio devices and headsets.
   {
     'master': 'WebRTCTryServer',
     'os': 'mac',
     'version': '10.10',
     'bits': '64',
     'builder': [
-      'mac_rel_xcode7',
-    ],
-    'hostname': 'vm1033-m4',
-  },
-  # Mac bare-metal machines with audio devices and headsets.
-  {
-    'master': 'WebRTCTryServer',
-    'os': 'mac',
-    'version': '10.8',
-    'bits': '64',
-    'builder': [
       'mac_baremetal',
     ],
     'hostname': 'build24-a4',
   }
 ] + [
   # Windows.
   {
     'master': 'WebRTCTryServer',
     'os': 'win',
     'version': 'win7',
@@ skipping 22 matching lines @@
     'master': 'WebRTCTryServer',
     'os': 'win',
     'version': 'win7',
     'bits': '64',
     'builder': [
       'win_baremetal',
     ],
     'hostname': 'build23-a4',
   }
 ]