Which IIT's(new as well as old) not taking interview or written test for MTech ECE branches admission this year (2019)?
I don't think there is any IIT that will admit you without a written test or at least a personal interview. The reason for this is that GATE exam depends heavily on multiple choice questions and sometimes students get such questions right simply by guessing. These tests and interviews help to re-assess the student's legitimate merit. However these written test scores only account for 10% of your admission eligibility, so don't worry about it too much.
Hope this helps :)