Update cassowary dependency to 0.1.7

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 16 matching lines @@
   'dart_revision': '2c4605c199fef683587fe1fd4a5fe67da6ba3308',
   'dart_observatory_packages_revision': '45565',
   'pdfium_revision': 'b0115665b0f33971f1b7077740d51e155583cec0',
   'boringssl_revision': '642f1498d056dbba3e50ed5a232ab2f482626dec',
   'lss_revision': 'e079768b7e3a94dcbe7d338496c0c3bde7151b6e',
   'nss_revision': 'bb4e75a43d007518ae7d618665ea2f25b0c60b63',
   'nacl_revision': '87d5dd90911a0657c27574f78e86b7dfc4ad8b29',
   'archive_dart_revision': '07ffd98c5403b7f9ae067b57dc9487611be420f5',
   'args_dart_revision': 'e0e8377412ee6cd6a5a4a8632848181c1db91f44',
   'box2d_dart_revision': 'c5e65d9546275e78ad2a1d51b459e7638f6e4323',
-  'cassowary_dart_revision': 'db724a65712fc36d626a73a1617aa6f118700a30',
+  'cassowary_dart_revision': '7e5afc5b3956a18636d5b37b1dcba1705865564b',
   'collection_dart_revision': '79ebc6fc2dae581cb23ad50a5c600c1b7dd132f8',
   'crypto_dart_revision': 'd4558dea1639e5ad2a41d045265b8ece270c2d90',
   'path_dart_revision': '2f3dcdec32011f1bc41194ae3640d6d9292a7096',
   'quiver_dart_revision': '6bab7dec34189eee579178eb16d3063c8ae69031',
   'source_span_dart_revision': '5c6c13f62fc111adaace3aeb4a38853d64481d06',
   'string_scanner_dart_revision': '9f00056b32f41efc376adecfb696a01bc7c593d7',
   'vector_math_dart_revision': '65915583f7aa606cb47ed265f853c18c60102b81',
   'yaml_dart_revision': 'd8c1ce75edf051ea1d5583b24474f8656abb4920',
 }
 
@@ skipping 362 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',
     ],
   },
 ]