Add vector_math and box2d as external Dart packages

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 13 matching lines @@
   'v8_revision': '230d131d173ab2d60291d303177bc04ec3f6e519',
   'angle_revision': 'bdd419f9f5b006e913606e7363125942c8ae06bc',
   'buildtools_revision': '15308f469a704c45d15567fa69cd94ce07ad0e1b',
   'dart_revision': '7c02eae5ec835c410682182bd380791f69b5eb8d',
   'dart_observatory_packages_revision': '45565',
   'pdfium_revision': 'b0115665b0f33971f1b7077740d51e155583cec0',
   'boringssl_revision': '642f1498d056dbba3e50ed5a232ab2f482626dec',
   'lss_revision': 'e079768b7e3a94dcbe7d338496c0c3bde7151b6e',
   'nss_revision': 'bb4e75a43d007518ae7d618665ea2f25b0c60b63',
   'nacl_revision': '87d5dd90911a0657c27574f78e86b7dfc4ad8b29',
+  'vector_math_dart_revision': '65915583f7aa606cb47ed265f853c18c60102b81',
+  'box2d_dart_revision': 'c5e65d9546275e78ad2a1d51b459e7638f6e4323',
 }
 
 # Only these hosts are allowed for dependencies in this DEPS file.
 # If you need to add a new host, contact chrome infrastructure team.
 allowed_hosts = [
   'boringssl.googlesource.com',
   'chromium.googlesource.com',
   'dart.googlecode.com',
   'pdfium.googlesource.com',
 ]
@@ skipping 49 matching lines @@
    'https://pdfium.googlesource.com/pdfium.git' + '@' +  Var('pdfium_revision'),
 
   'src/third_party/boringssl/src':
    'https://boringssl.googlesource.com/boringssl.git' + '@' +  Var('boringssl_revision'),
 
   'src/third_party/requests/src':
     Var('chromium_git') + '/external/github.com/kennethreitz/requests.git' + '@' + 'f172b30356d821d180fa4ecfa3e71c7274a32de4',
 
   'src/native_client':
     Var('chromium_git') + '/native_client/src/native_client.git' + '@' + Var('nacl_revision'),
+
+  'src/third_party/dart-pkg/vector_math':
+      Var('chromium_git') + '/external/github.com/google/vector_math.dart.git' + '@' + Var('vector_math_dart_revision'),
+
+  'src/third_party/dart-pkg/box2d':
+      Var('chromium_git') + '/external/github.com/google/box2d.dart.git' + '@' + Var('box2d_dart_revision'),
 }
 
 
 deps_os = {
   'android': {
     'src/third_party/colorama/src':
      Var('chromium_git') + '/external/colorama.git' + '@' + '799604a1041e9b3bc5d2789ecbd7e8db2e18e6b8',
 
     'src/third_party/jsr-305/src':
         Var('chromium_git') + '/external/jsr-305.git' + '@' + '642c508235471f7220af6d5df2d3210e3bfc0919',
@@ skipping 239 matching lines @@
     'name': 'dejavu-fonts',
     'pattern': '',
     'action': [ 'download_from_google_storage',
                 '--no_resume',
                 '--no_auth',
                 '--bucket', 'mojo/dejavu-fonts',
                 '-s', 'src/third_party/dejavu-fonts-ttf-2.34/ttf/DejaVuSansMono.ttf.sha1',
     ],
   },
 ]