clang-format: [JS] supports casts to types starting with punctuation ("{[(").

Before:

    x as{x: number}

After:

    x as {x: number}

Reviewers: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D23761

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@279436 91177308-0d34-0410-b5e6-96231b3b80d8