It’s not every day that someone tries to add a new programming language to the web. There’s a good reason for that. The great trinity of web development — HTML, CSS and JavaScript — while not perfect, has proved itself highly flexible and capable of adapting as it evolves, which, in the end, might be more important than perfection.

But, regardless of how well those three have served the web thus far, they are not enough for Google, which is hoping the web will now embrace Dart, Google’s brand-new programming language for “structured web programming.”

The first hint of Dart surfaced about a...