Highlighted user input focused

[edemattos]

When a user receives feedback, the contenteditable may contain a span element with highlighted text. If the user wishes to modify their answer, the highlighting should behave in one of two ways:

1. Only remove the span tags (containing a CSS style class to add background color) if the inner text has been modified. This can potentially be achieved with an event listener listening for a state change within the span content. (preferable)
2. Remove the span immediately once the answer is changed at all, regardless of what has been changed.

The highlighted user input (span element) can be retrieved using `${contentID}_${fieldID}_input_highlight` and checking to make sure element !== null. Removing the highlight span could probably be accomplished by replacing the highlightPattern regex with an empty string.