Bug 932281 - Extend TelemetryHistogram.{id_offset, comment_offset} to uint32_t. r=nfroyd, a=bustage

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extra : source : e91a4b7fbb2fcff64fefe7c6532f42a935e2183a
extra : amend_source : 12db91f1b213ae1266bb402bc88a302791b37d2a