Interesting idea, I kind of like it.  I don't think it necessarily goes _against_ semantic versioning if we wait and stay under 1.0.0 until we have 100% chrome coverage.  Under version 1 we can do what we like (according to semver) and then 28 -> 29 -> 30 -> etc... would match the Chrome version cycle.  I don't think that breaks semver but I haven't looked at the fine print in a while.