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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280730 91177308-0d34-0410-b5e6-96231b3b80d8