[telemetry] Add a webdriver backend with support for IE.

tools/telemetry/telemetry/core/util.py

Index: tools/telemetry/telemetry/core/util.py
diff --git a/tools/telemetry/telemetry/core/util.py b/tools/telemetry/telemetry/core/util.py
index 2fe792feccc02b74fc9e685053f7cf7d0d366dfa..92423dcacbe698b77e5f72dd836f50fca840ca42 100644
--- a/tools/telemetry/telemetry/core/util.py
+++ b/tools/telemetry/telemetry/core/util.py
@@ -70,6 +70,18 @@ class PortPair(object):
     self.local_port = local_port
     self.remote_port = remote_port
 
+class DoNothingForwarder(object):
+  def __init__(self, *port_pairs):
+    self._host_port = port_pairs[0].local_port
+
+  @property
+  def url(self):
+    assert self._host_port
+    return 'http://127.0.0.1:%i' % self._host_port
+
+  def Close(self):
+    self._host_port = None
+
 def GetAvailableLocalPort():
   tmp = socket.socket()
   tmp.bind(('', 0))