If you pick up FTL on the Humble Store you should be able to play it on their website in a web browser.

edit 01: [screenshots]

1) https://screenshots.firefox.com/YJvULhgFlPJKtpD1/www.humbleb...

2) https://screenshots.firefox.com/UMQMitQ4Rm4viSlv/www.humbleb...

edit 02: To play it in a separate tabs as per the scrots just take the key from the purchase page https://www.humblebundle.com/downloads?key=foobarXXXX and apply it to this url like so https://www.humblebundle.com/play/asmjs/ftl_asm/foobarXXXX

As a bonus this allows you to play it on any computer without logging in.