chromium_tests: fix crash in deapply_patch on got_webkit_revision

scripts/slave/recipes/dart/dartium_perf.expected/basic_win_64_MirrorTrue.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]\\gclient.py",
       "config",
       "--spec",
       "cache_dir = None\nsolutions = [{'custom_vars': {'dartium_base': 'svn://svn-mirror.golo.chromium.org', 'googlecode_url': 'svn://svn-mirror.golo.chromium.org/%s', 'nacl_trunk': 'svn://svn-mirror.golo.chromium.org/native_client/trunk', 'sourceforge_url': 'svn://svn-mirror.golo.chromium.org/%(repo)s', 'webkit_trunk': 'svn://svn-mirror.golo.chromium.org/blink/trunk'}, 'deps_file': 'DEPS', 'managed': True, 'name': 'dartium.deps', 'url': 'svn://svn-mirror.golo.chromium.org/dart/branches/bleeding_edge/deps/dartium.deps'}]"
     ],
@@ skipping 22 matching lines @@
       "@@@STEP_LOG_LINE@json.output@  \"solutions\": {@@@",
       "@@@STEP_LOG_LINE@json.output@    \"dartium.deps/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 10382@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/dart/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 58622@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/native_client/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 274981@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
-      "@@@STEP_LOG_LINE@json.output@    \"src/third_party/WebKit/\": {@@@",
-      "@@@STEP_LOG_LINE@json.output@      \"revision\": 124383@@@",
-      "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/third_party/webrtc/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 120644@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/tools/swarming_client/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 276089@@@",
       "@@@STEP_LOG_LINE@json.output@    }, @@@",
       "@@@STEP_LOG_LINE@json.output@    \"src/v8/\": {@@@",
       "@@@STEP_LOG_LINE@json.output@      \"revision\": 43426@@@",
       "@@@STEP_LOG_LINE@json.output@    }@@@",
       "@@@STEP_LOG_LINE@json.output@  }@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
-      "@@@SET_BUILD_PROPERTY@got_nacl_revision@274981@@@",
-      "@@@SET_BUILD_PROPERTY@got_webkit_revision@124383@@@",
-      "@@@SET_BUILD_PROPERTY@got_swarming_client_revision@276089@@@",
       "@@@SET_BUILD_PROPERTY@got_webrtc_revision@120644@@@",
       "@@@SET_BUILD_PROPERTY@got_revision@58622@@@",
-      "@@@SET_BUILD_PROPERTY@got_v8_revision@43426@@@"
+      "@@@SET_BUILD_PROPERTY@got_nacl_revision@274981@@@",
+      "@@@SET_BUILD_PROPERTY@got_v8_revision@43426@@@",
+      "@@@SET_BUILD_PROPERTY@got_swarming_client_revision@276089@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]\\gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
@@ skipping 549 matching lines @@
       "--build-number=571",
       "--run-python-script",
       "--revision=12345",
       "[BUILD]\\scripts\\slave\\telemetry.py",
       "--factory-properties={\"browser_exe\": \"[SLAVE_BUILD]\\\\src\\\\out\\\\Release_x64\\\\chrome.exe\", \"blink_config\": \"chromium\", \"expectations\": true, \"show_perf_results\": true, \"test_name\": \"sunspider\", \"tools_dir\": \"[SLAVE_BUILD]\\\\src\\\\tools\", \"target_platform\": \"win32\", \"target_os\": null, \"halt_on_missing_build\": true, \"target\": \"Release\", \"run_reference_build\": true, \"build_dir\": \"src/out\", \"step_name\": \"sunspider\", \"reference_build_executable\": \"src/chrome/tools/refbuild/chrome\"}"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "sunspider"
   }
 ]