Misleading deprecation warning & superfluous dummy input

[NeilFraser]

Describe the bug

Loading the lists_repeat block in German prints this warning in the console:

"Deprecated use of setting size_.width to 0 to rerender a field. Set field.isDirty_ to true instead."

The block in question does no such thing.

To Reproduce

1. Go to https://blockly-demo.appspot.com/static/demos/code/index.html?lang=de
2. Click on 'Listen'
3. See warning in the console.

Expected behaviour

No console warning.

Additional context

The English version of the block does not generate this warning. The difference between the two is that English has a text label containing the word "times" at the end of the block, whereas the German block inexplicably has a dummy input with a text label containing the empty string:

"LISTS_REPEAT_TITLE": "create list with item %1 repeated %2 times",
"LISTS_REPEAT_TITLE": "erzeuge Liste mit %2-mal dem Element %1​",

Thus I think there are two issues here:

1. A misleading warning that's being printed when using an empty text label.
2. JSON-created blocks are creating unwanted dummy inputs with empty text labels.

Found while testing Blockly Games. This is not a new error (at least a year old).

[NeilFraser]

Found the source of the error. There's an invisible zero width space character (U+200B) in the German version of LISTS_REPEAT_TITLE.

[NeilFraser]

Fixed both issues. Also contacted Translatewiki to suggest an upstream filter for zero-width space characters.