Support running with mojo:debugger in devtools.

mojo/devtools/common/devtoolslib/linux_shell.py

Index: mojo/devtools/common/devtoolslib/linux_shell.py
diff --git a/mojo/devtools/common/devtoolslib/linux_shell.py b/mojo/devtools/common/devtoolslib/linux_shell.py
index 4b3d98a4cd2ef636807a1620f8db2db4fb869dd4..5c086d97b6181f8e6be023fa48fa596f543a1aea 100644
--- a/mojo/devtools/common/devtoolslib/linux_shell.py
+++ b/mojo/devtools/common/devtoolslib/linux_shell.py
@@ -37,6 +37,14 @@ class LinuxShell(Shell):
     """
     return 'http://%s:%d/' % http_server.StartHttpServer(local_dir_path, port)
 
+  def ForwardHostPortToShell(self, host_port):
+    """Forwards a port on the host machine to the same port wherever the shell
+    is running.
+
+    This is a no-op if the shell is running locally.
+    """
+    pass
+
   def Run(self, arguments):
     """Runs the shell with given arguments until shell exits, passing the stdout
     mingled with stderr produced by the shell onto the stdout.