Remove Sky-specific hooks that no longer work

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of 'src').
 #
@@ skipping 277 matching lines @@
     'name': 'clang_format_mac',
     'pattern': '.',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--platform=darwin',
                 '--no_auth',
                 '--bucket', 'chromium-clang-format',
                 '-s', 'src/buildtools/mac/clang-format.sha1',
     ],
   },
-  # Pull sky_server binaries using checked-in hashes.
-  {
-    'name': 'sky_server_linux',
-    'pattern': '.',
-    'action': [ 'download_from_google_storage',
-                '--no_resume',
-                '--platform=linux*',
-                '--no_auth',
-                '--bucket', 'mojo',
-                '-s', 'src/sky/tools/skygo/linux64/sky_server.sha1',
-    ],
-  },
-  {
-    'name': 'sky_server_mac',
-    'pattern': '.',
-    'action': [ 'download_from_google_storage',
-                '--no_resume',
-                '--platform=darwin',
-                '--no_auth',
-                '--bucket', 'mojo',
-                '-s', 'src/sky/tools/skygo/mac/sky_server.sha1',
-    ],
-  },
-  {
-    'name': 'material_design_icons',
-    'pattern': '.',
-    'action': [
-        'python',
-        'src/sky/sdk/lib/download_material_design_icons',
-    ],
-  },
   # Pull binutils for linux, enabled debug fission for faster linking /
   # debugging when used with clang on Ubuntu Precise.
   # https://code.google.com/p/chromium/issues/detail?id=352046
   {
     'name': 'binutils',
     'pattern': 'src/third_party/binutils',
     'action': [
         'python',
         'src/third_party/binutils/download.py',
     ],
@@ skipping 82 matching lines @@
     'name': 'keyboard_native_resources',
     'pattern': '',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--no_auth',
                 '--bucket', 'mojo/keyboard_native',
                 '-d', 'src/services/keyboard_native/res',
     ],
   },
 ]