While not a source control system, the JetBrains IDEs have a very good merge tool that is filetype aware. For example, WebStorm/IntelliJ Ultimate, when merging JavaScript, often has a "magic wand" option that can detect when merge conflicts are actually resolvable if you parse both sides first, and merge the AST.

It doesn't always work quite right, but it's good enough that I use it quite often.