clang-format: [JS] space between pseudo keywords and template literals.

Summary:
Before:
    yield`foo`;

After:
    yield `foo`;

Reviewers: djasper

Subscribers: klimek

Differential Revision: https://reviews.llvm.org/D34938

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@307023 91177308-0d34-0410-b5e6-96231b3b80d8