OriginalValue has invalid initial value

[edloidas]

When the FormInputEl is initialized,originalValue is assigned to undefined if not set during initialization. But if we call resetBaseValues() it will be assigned to "" (if input is empty), because this.getValue() returns "" for empty input.
But if we check the dirty state, originalValue will be wrapped in string object and return "undefined" and later compared to empty input value "". This is not correct at all.
Initial value for originalValue must be an empty string, and the value itself must not be wrapped in String, as it either a string, or null/undefined by default.