input[type=number], input[type=date], input[type=time], etc. have locale-dependent behavior. However we can't test them in a specific locale in LayoutTests for now. We'd like to introduce a mechanism to make it possible.
This bug has some relationship to Bug 11008. But we focus on only testing in this bug.
The remaining task is to add multiple locale support to LocalizedStrings.h, and it is very hard. We'd like to address it when we fix Bug 11008.