Safari issue with multiple input elements in Numeric or Calculated question types

Given a FIN or Calc question, input elements are contained in a label element. The parent label element has `for` attribute equal to the id of its first input (child element).

In Safari, having multiple inputs as children presents a problem whereby the first input always gets focus whenever another sibling input is clicked. Users thus need to tab thru the inputs to answer questions.

The issue is related to SAM-3131, and the changes in that commit need to be propagated to FIN and Calc question types.