clang-format: [JS] Fix line breaks in computed property names.

Before:
  let foo = {
    [someLongKeyHere]: 1,
    someOtherLongKeyHere: 2, [keyLongEnoughToWrap]: 3,
    lastLongKey: 4
  };

After:
  let foo = {
    [someLongKeyHere]: 1,
    someOtherLongKeyHere: 2,
    [keyLongEnoughToWrap]: 3,
    lastLongKey: 4
  };

llvm-svn: 238671