When you create the html5 project from Central and then run it on AS7 (Project -> Run As -> Run on server) it is opened in the internal browser by default. For some reason the application thinks the eclipse internal browser is a mobile device and displays it as such. I'm pretty sure it worked correctly in the past.
I assume usually this is controlled by the user agent http header.
I checked the access_log on a server I own and this is what I get:
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/536.26.14 (KHTML, like Gecko) Safari/522.0"
When I just used Safari to display the html5 project, I saw this in the access_log:
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/536.26.17 (KHTML, like Gecko) Version/6.0.2 Safari/536.26.17"