Updated to latest WebKit changes and removed usage of obsolete environment variable

TBR=whesse@google.com

Review URL: https://codereview.chromium.org/2413253002 .

tools/dartium/test.py

@@ -194,7 +194,6 @@ def main():
             test = os.path.join(DART_TEST_DIR, options.layout_test)
           else:
             test = DART_TEST_DIR
-          package_root = os.path.join(build_dir, 'packages')
           utils.runCommand(['python',
                             test_script,
                             test_mode,
@@ -204,8 +203,6 @@ def main():
                             '--builder-name', 'BuildBot',
                             '--additional-env-var',
                             'DART_FLAGS=%s' % dart_flags,
-                            '--additional-env-var',
-                            'DART_PACKAGE_ROOT=file://%s' % package_root,
                             test])
 
         # Run core dart tests

tools/deps/dartium.deps/DEPS

@@ -9,7 +9,7 @@ execfile(os.path.join(path, 'src', 'dart', 'tools', 'deps', 'dartium.deps', 'DEP
 
 vars.update({
   "dartium_chromium_commit": "7558afb6379171d7f96b2db68ae9d2b64b2c5544",
-  "dartium_webkit_commit": "8c0535e2ee1f49410cb978bd7c18d4582a5fd886",
+  "dartium_webkit_commit": "4cc16a03bf8c40ec67bff039b7fc80ed608d7604",
   "chromium_base_revision": "338390",
 
   # We use mirrors of all github repos to guarantee reproducibility and