clang-format: [JS] Improve formatting of function literals in chains

Before:
  getSomeLongPromise(.....)
      .then(
           function(value) {
             body();
             body();
           })
      .thenCatch(function(error) {
    body();
    body();
  });

After:
  getSomeLongPromise(.....)
      .then(function(value) {
        body();
        body();
      })
      .thenCatch(function(error) {
        body();
        body();
      });

llvm-svn: 218595