--- a/layout/forms/nsListControlFrame.cpp
+++ b/layout/forms/nsListControlFrame.cpp
@@ -1117,31 +1117,40 @@ nsListControlFrame::GetCurrentOption()
   // the selected index if this is kNothingSelected.
   int32_t focusedIndex = (mEndSelectionIndex == kNothingSelected) ?
     GetSelectedIndex() : mEndSelectionIndex;
 
   if (focusedIndex != kNothingSelected) {
     return GetOption(AssertedCast<uint32_t>(focusedIndex));
   }
 
-  // There is no selected item. Return the first non-disabled item.
+  // There is no selected option. Return the first non-disabled option, if any.
+  return GetNonDisabledOptionFrom(0);
+}
+
+HTMLOptionElement*
+nsListControlFrame::GetNonDisabledOptionFrom(int32_t aFromIndex,
+                                             int32_t* aFoundIndex)
+{
   RefPtr<dom::HTMLSelectElement> selectElement =
     dom::HTMLSelectElement::FromContent(mContent);
 
-  for (uint32_t i = 0, length = selectElement->Length(); i < length; ++i) {
-    dom::HTMLOptionElement* node = selectElement->Item(i);
+  const uint32_t length = selectElement->Length();
+  for (uint32_t i = std::max(aFromIndex, 0); i < length; ++i) {
+    HTMLOptionElement* node = selectElement->Item(i);
     if (!node) {
-      return nullptr;
+      break;
     }
-
     if (!selectElement->IsOptionDisabled(node)) {
+      if (aFoundIndex) {
+        *aFoundIndex = i;
+      }
       return node;
     }
   }
-
   return nullptr;
 }
 
 bool
 nsListControlFrame::IsInDropDownMode() const
 {
   return (mComboboxFrame != nullptr);
 }
@@ -2474,17 +2483,27 @@ nsListControlFrame::KeyPress(nsIDOMEvent
 
 void
 nsListControlFrame::PostHandleKeyEvent(int32_t aNewIndex,
                                        uint32_t aCharCode,
                                        bool aIsShift,
                                        bool aIsControlOrMeta)
 {
   if (aNewIndex == kNothingSelected) {
-    return;
+    int32_t focusedIndex = mEndSelectionIndex == kNothingSelected ?
+      GetSelectedIndex() : mEndSelectionIndex;
+    if (focusedIndex != kNothingSelected) {
+      return;
+    }
+    // No options are selected.  In this case the focus ring is on the first
+    // non-disabled option (if any), so we should behave as if that's the option
+    // the user acted on.
+    if (!GetNonDisabledOptionFrom(0, &aNewIndex)) {
+      return;
+    }
   }
 
   // If you hold control, but not shift, no key will actually do anything
   // except space.
   nsWeakFrame weakFrame(this);
   bool wasChanged = false;
   if (aIsControlOrMeta && !aIsShift && aCharCode != ' ') {
     mStartSelectionIndex = aNewIndex;

--- a/layout/forms/nsListControlFrame.h
+++ b/layout/forms/nsListControlFrame.h
@@ -44,16 +44,18 @@ class HTMLOptionsCollection;
  */
 
 class nsListControlFrame final : public nsHTMLScrollFrame,
                                  public nsIFormControlFrame,
                                  public nsIListControlFrame,
                                  public nsISelectControlFrame
 {
 public:
+  typedef mozilla::dom::HTMLOptionElement HTMLOptionElement;
+
   friend nsContainerFrame* NS_NewListControlFrame(nsIPresShell* aPresShell,
                                                   nsStyleContext* aContext);
 
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS
 
     // nsIFrame
   virtual nsresult HandleEvent(nsPresContext* aPresContext,
@@ -113,17 +115,17 @@ public:
     // for accessibility purposes
 #ifdef ACCESSIBILITY
   virtual mozilla::a11y::AccType AccessibleType() override;
 #endif
 
     // nsIListControlFrame
   virtual void SetComboboxFrame(nsIFrame* aComboboxFrame) override;
   virtual int32_t GetSelectedIndex() override;
-  virtual mozilla::dom::HTMLOptionElement* GetCurrentOption() override;
+  virtual HTMLOptionElement* GetCurrentOption() override;
 
   /**
    * Gets the text of the currently selected item.
    * If the there are zero items then an empty string is returned
    * If there is nothing selected, then the 0th item's text is returned.
    */
   virtual void GetOptionText(uint32_t aIndex, nsAString& aStr) override;
 
@@ -175,17 +177,17 @@ public:
 
   /**
    * Returns the options collection for mContent, if any.
    */
   mozilla::dom::HTMLOptionsCollection* GetOptions() const;
   /**
    * Returns the HTMLOptionElement for a given index in mContent's collection.
    */
-  mozilla::dom::HTMLOptionElement* GetOption(uint32_t aIndex) const;
+  HTMLOptionElement* GetOption(uint32_t aIndex) const;
 
   static void ComboboxFocusSet();
 
   // Helper
   bool IsFocused() { return this == mFocused; }
 
   /**
    * Function to paint the focus rect when our nsSelectsAreaFrame is painting.
@@ -253,16 +255,23 @@ public:
    * fire a native focus event for accessibility
    * (Some 3rd party products need to track our focus)
    */
   void FireMenuItemActiveEvent(); // Inform assistive tech what got focused
 #endif
 
 protected:
   /**
+   * Return the first non-disabled option starting at aFromIndex (inclusive).
+   * @param aFoundIndex if non-null, set to the index of the returned option 
+   */
+  HTMLOptionElement* GetNonDisabledOptionFrom(int32_t aFromIndex,
+                                              int32_t* aFoundIndex = nullptr);
+
+  /**
    * Updates the selected text in a combobox and then calls FireOnChange().
    * @note This method might destroy the frame, pres shell and other objects.
    * Returns false if calling it destroyed |this|.
    */
   bool       UpdateSelection();
 
   /**
    * Returns whether mContent supports multiple selection.
@@ -277,17 +286,17 @@ protected:
    * @note This method might destroy the frame, pres shell and other objects.
    */
   void       DropDownToggleKey(nsIDOMEvent* aKeyEvent);
 
   nsresult   IsOptionDisabled(int32_t anIndex, bool &aIsDisabled);
   /**
    * @note This method might destroy the frame, pres shell and other objects.
    */
-  void ScrollToFrame(mozilla::dom::HTMLOptionElement& aOptElement);
+  void ScrollToFrame(HTMLOptionElement& aOptElement);
   /**
    * @note This method might destroy the frame, pres shell and other objects.
    */
   void ScrollToIndex(int32_t anIndex);
 
   /**
    * When the user clicks on the comboboxframe to show the dropdown
    * listbox, they then have to move the mouse into the list. We don't