LibWeb: Use correct value when parsing datetime-local input type

Author: https://github.com/tcl3
Commit: eb4e40bc49
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1360
Reviewed-by: https://github.com/trflynn89 ✅

Tests/LibWeb/Text/expected/HTML/HTMLInputElement-valueAsNumber.txt

@@ -33,7 +33,7 @@ date did not throw: NaN
 month did not throw: NaN
 week did not throw: NaN
 time did not throw: NaN
-datetime-local threw exception: InvalidStateError: valueAsNumber: Invalid input type used
+datetime-local did not throw: NaN
 number did not throw: 100
 range did not throw: 100
 color threw exception: InvalidStateError: valueAsNumber: Invalid input type used