har_dump.py does not convert the req-res in order they were exchanged.

Steps to reproduce the problem:

1.visit 10 sites one after other. capture the dump using mitmdump.
2.convert the dump to har format using har_dump.py
3.the order in which the GET request to sites appear in har is not same as the order they were visited,
or the order which appears in mitmproxy console when we load the captured dump file
Any other comments? What have you tried so far?
System information

Mitmproxy: 3.0.4 binary
Python: 3.6.3
OpenSSL: OpenSSL 1.1.0h 27 Mar 2018
Platform: Linux-4.10.0-42-generic-x86_64-with-debian-stretch-sid

Hi, this is already reported and tracked at https://github.com/mitmproxy/mitmproxy/issues/3060, no need to repeat it here. :wink: