And refine uncommon date cases.

# Iteration per second (i/s)

|                            |compare-ruby|built-ruby|
|:---------------------------|-----------:|---------:|
|time.xmlschema              |      5.020M|   14.192M|
|                            |           -|     2.83x|
|utc_time.xmlschema          |      6.454M|   15.331M|
|                            |           -|     2.38x|
|time.xmlschema(6)           |      4.216M|   10.043M|
|                            |           -|     2.38x|
|utc_time.xmlschema(6)       |      5.486M|   10.592M|
|                            |           -|     1.93x|
|time.xmlschema(9)           |      4.294M|   10.340M|
|                            |           -|     2.41x|
|utc_time.xmlschema(9)       |      4.784M|   10.909M|
|                            |           -|     2.28x|
|fraction_sec.xmlschema(10)  |    366.982k|    3.406M|
|                            |           -|     9.28x|
|future_time.xmlschema       |    994.595k|   15.853M|
|                            |           -|    15.94x|