These flaws are inhibiting development of the kinds of complex web apps Google specialises in, says the email, purported to have been written by Googler Mark S Miller and available on Github.
It's unclear whether the email is genuine and Google had not responded to a request for comment at the time of publication.
At least one of the people also named in the email has, however, called the document a "draft" adding it doesn't necessarily reflect his personal views.
Details on Dart on the Goto conference site were brief and Google has not officially said anything. Goto called Dart: "A new programming language for structured web programming."
According to the email, though, Dash has been designed to hit three objectives: improved performance, developer usability and what Google is calling the "ability to be tooled".
Translated that last bit means an ability to be used with tools for coding activities such as refactoring used in large-scale programming projects.
It won't be an easy job, as the leaked email concedes: "This will be a difficult effort requiring finesse and determination, but we are committed to doing everything possible to help it succeed."
Driving Dash/Dart is Google's fear of Apple and the rise of the closed web and what that could mean to Google as a programming platform for accessing the web. Google is apparently concerned innovation is moving off the web as we and Tim Berners-Lee know it, and on to the popular but fenced-off iPhone and iPad. That poses a huge problem for Google when you've built a search and ads empire on a web without fences.
According to the email:
The language has been designed to be consumed in the browser VM, on the front-end server and different compilers. Google has folded the team behind its JSPrime successor to GWT into the effort building the new language, while Joy will be built in to provide templating and model-view controller (MVC) features for code development. ®