Bug 675943 - Part 3: Clean up after implementing dirname. r=edgar

Depends on D178164

Differential Revision: https://phabricator.services.mozilla.com/D178278

dom/html/nsGenericHTMLElement.cpp

@@ -24,6 +24,7 @@
 #include "mozilla/StaticPrefs_layout.h"
 #include "mozilla/StaticPrefs_accessibility.h"
 
+#include "mozilla/dom/FormData.h"
 #include "nscore.h"
 #include "nsGenericHTMLElement.h"
 #include "nsAttrValueInlines.h"
@@ -2824,6 +2825,23 @@ bool nsGenericHTMLFormControlElement::IsAutocapitalizeInheriting() const {
          type == FormControlType::Select || type == FormControlType::Textarea;
 }
 
+nsresult nsGenericHTMLFormControlElement::SubmitDirnameDir(
+    FormData* aFormData) {
+  // Submit dirname=dir if element has non-empty dirname attribute
+  if (HasAttr(kNameSpaceID_None, nsGkAtoms::dirname)) {
+    nsAutoString dirname;
+    GetAttr(kNameSpaceID_None, nsGkAtoms::dirname, dirname);
+    if (!dirname.IsEmpty()) {
+      const Directionality eDir = GetDirectionality();
+      MOZ_ASSERT(eDir == eDir_RTL || eDir == eDir_LTR,
+                 "The directionality of an element is either ltr or rtl");
+      const nsString dir = eDir == eDir_LTR ? u"ltr"_ns : u"rtl"_ns;
+      return aFormData->AddNameValuePair(dirname, dir);
+    }
+  }
+  return NS_OK;
+}
+
 //----------------------------------------------------------------------
 
 static const nsAttrValue::EnumTable kPopoverTargetActionTable[] = {