How can I use web.whatsapp.com on an Android phone with a broken screen? My Android phone's screen died: no image, no touch, nada. How can I use http://web.whatsapp.com/ without being able to start WhatsApp and browse to the option Menu > Whatsapp Web so I can scan the QR Code on the web page?

This is obviously an interim solution until my new phone arrives.
Directly start WhatsApp with the correct activity intent via ADB:

adb shell "su -c 'am start com.whatsapp/.qrcode.QrCodeActivity'"


Then hold your camera in front of the QR Code @ http://web.whatsapp.com/.

Requirements: 


a rooted Android phone (outside scope of this post)  
working adb (like Minimal ADB + Fastboot or ADB for Chrome)  
working SuperUser su binary


Found it with something along the lines of:

adb shell "su -c 'find /data -name *whatsapp*.dex | xargs strings | grep Qr'"