A front component rendering a numeric input never showed its value
because the caret-preserving path only accepted strings:
- controlled: `<input type="number" value={42}>` was rejected by the
value sync guard, so nothing was written to the host element
- uncontrolled: `defaultValue={42}` was dropped from the initial value
seeding
Numeric values are now stringified in both places. Also adds a test
asserting `createCaretPreservingElement` forwards its ref to the
rendered element.
The controlled case and the ref test were flagged by cubic on #23264
Raphaël Bosi
64001591f2