[clang-format] don't break between function and function name in JS

The patch https://reviews.llvm.org/D105964 (https://github.com/llvm/llvm-project/commit/58494c856a15f5b0e886c7baf5d505ac6c05dfe5)
updated detection of function declaration names. It had the unfortunate
consequence that it started breaking between `function` and the function
name in some cases in JavaScript code.

This patch addresses this.

Reviewed By: MyDeveloperDay, owenpan

Differential Revision: https://reviews.llvm.org/D107267