Fix calculation of direction for text form control elements with dir=…

…"auto"

https://bugs.webkit.org/show_bug.cgi?id=245718

Reviewed by Ryosuke Niwa.

For elements with dir="auto", HTMLTextFormControlElement::directionForFormData()
is relying on HTMLElement::directionalityIfDirIsAuto() but this function may
sometimes return a nullopt, so add a fallback value.

* Source/WebCore/html/HTMLTextFormControlElement.cpp:
(WebCore::HTMLTextFormControlElement::directionForFormData const): Fallback to
  LTR when directionalityIfDirIsAuto() returns a nullopt.

Canonical link: https://commits.webkit.org/254943@main

Source/WebCore/html/HTMLTextFormControlElement.cpp

@@ -822,7 +822,7 @@ String HTMLTextFormControlElement::directionForFormData() const
             if (equalLettersIgnoringASCIICase(value, "ltr"_s))
                 return TextDirection::LTR;
             if (equalLettersIgnoringASCIICase(value, "auto"_s))
-                return element.directionalityIfDirIsAuto().value();
+                return element.directionalityIfDirIsAuto().value_or(TextDirection::LTR);
         }
         return TextDirection::LTR;
     }();