Revert "Remove unused f expression from jscode gen. (#5573)"
Revert "Remove unused f expression from jscode gen. (#5573)"

The removed variable here is actually used breaking downstream bazel
builds.

google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf