Syntax highlighting in BUILD files

I don't get syntax highlighting only in `BUILD` files (language mode defaults to "Plain text").
If I rename my file to `BUILD.bazel`, the syntax highlighting turns on.

Reproduce the issue in VS Code with a file named BUILD and compare it with BUILD.bazel, focusing on the extension's language-association entry point. Done means BUILD files receive the same Bazel syntax highlighting as BUILD.bazel files; the issue does not name a specific source file or test.

Written by the indexing model from the issue text.