webkitpy: Reduce usage of path_from_webkit_base().

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
index c0efd2a06333b1d7bdfcffe865a3308e1698b043..e77cca15f9c77e9f7fbc884796956c5098a2a209 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
@@ -7,6 +7,7 @@
 import datetime
 import logging
 
+from webkitpy.common.webkit_finder import WebKitFinder
 from webkitpy.layout_tests.servers import server_base
 
 
@@ -32,8 +33,9 @@ class WPTServe(server_base.ServerBase):
         fs = self._filesystem
         self._pid_file = fs.join(self._runtime_path, '%s.pid' % self._name)
 
-        path_to_thirdparty = self._port_obj.path_from_webkit_base('Tools', 'Scripts', 'webkitpy', 'thirdparty')
-        path_to_wpt_support = self._port_obj.path_from_webkit_base('Tools', 'Scripts', 'webkitpy', 'thirdparty', 'wpt')
+        finder = WebKitFinder(fs)
+        path_to_thirdparty = finder.path_from_tools_scripts('webkitpy', 'thirdparty')
+        path_to_wpt_support = finder.path_from_tools_scripts('webkitpy', 'thirdparty', 'wpt')
         path_to_wpt_root = fs.join(path_to_wpt_support, 'wpt')
         path_to_wpt_config = fs.join(path_to_wpt_support, 'wpt.config.json')
         path_to_wpt_tests = fs.abspath(fs.join(self._port_obj.layout_tests_dir(), 'external', 'wpt'))