`intSizes` of Registers sums up values instead of length of values

[yzhang90]

rule intSizes(ARR, I, J) => getInt(ARR [ J ]) +Int intSizes(ARR, I, J +Int 1) [owise] should be
rule intSizes(ARR, I, J) => intSize(getInt(ARR [ J ])) +Int intSizes(ARR, I, J +Int 1) [owise]

[dwightguth]

This needs to be fixed in a backwards compatible way.