clang-format: [JS] ignore comments when wrapping returns.

Summary:
When code contains a comment between `return` and the value:

    return /* lengthy comment here */ (
        lengthyValueComesHere);

Do not wrap before the comment, as that'd break the code through JS' automatic
semicolon insertion.

Reviewers: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D24257

llvm-svn: 280730