webkitpy: Don't fail if importing a port fails.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py
index 95d2454f0563cfe69dc3b63507292284845ea823..05d7bc33febb580903b5f266e3de6d65f470dbcd 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/factory.py
@@ -31,6 +31,7 @@
 import fnmatch
 import optparse
 import re
+import warnings
 
 from webkitpy.common.webkit_finder import WebKitFinder
 
@@ -162,7 +163,12 @@ class PortFactory(object):
         else:
             for port_class in self.PORT_CLASSES:
                 module_name, class_name = port_class.rsplit('.', 1)
-                module = __import__(module_name, globals(), locals(), [], -1)
+                try:
+                    module = __import__(module_name, globals(), locals(), [], -1)
+                except ImportError as exp:
+                    warnings.warn(
+                        'Unable to import %s (%s)' % (module_name, exp), stacklevel=2)
+                    continue
                 cls = module.__dict__[class_name]
                 if port_name.startswith(cls.port_name):
                     port_name = cls.determine_full_port_name(self._host, options, port_name)