--- a/layout/forms/nsComboboxControlFrame.cpp
+++ b/layout/forms/nsComboboxControlFrame.cpp
@@ -50,18 +50,18 @@ nsComboboxControlFrame::RedisplayTextEve
 }
 
 class nsPresState;
 
 #define FIX_FOR_BUG_53259
 
 // Drop down list event management.
 // The combo box uses the following strategy for managing the drop-down list.
-// If the combo box or it's arrow button is clicked on the drop-down list is displayed
-// If mouse exit's the combo box with the drop-down list displayed the drop-down list
+// If the combo box or its arrow button is clicked on the drop-down list is displayed
+// If mouse exits the combo box with the drop-down list displayed the drop-down list
 // is asked to capture events
 // The drop-down list will capture all events including mouse down and up and will always
 // return with ListWasSelected method call regardless of whether an item in the list was
 // actually selected.
 // The ListWasSelected code will turn off mouse-capture for the drop-down list.
 // The drop-down list does not explicitly set capture when it is in the drop-down mode.
 
 
@@ -440,17 +440,17 @@ nsComboboxControlFrame::ReflowDropdown(n
   }
   nsRect rect = mDropdownFrame->GetRect();
   nsHTMLReflowMetrics desiredSize(aReflowState.GetWritingMode());
   nsReflowStatus ignoredStatus;
   nsresult rv = ReflowChild(mDropdownFrame, aPresContext, desiredSize,
                             kidReflowState, rect.x, rect.y, flags,
                             ignoredStatus);
 
-   // Set the child's width and height to it's desired size
+   // Set the child's width and height to its desired size
   FinishReflowChild(mDropdownFrame, aPresContext, &kidReflowState,
                     desiredSize, rect.x, rect.y, flags);
   return rv;
 }
 
 nsPoint
 nsComboboxControlFrame::GetCSSTransformTranslation()
 {
@@ -1133,17 +1133,17 @@ nsComboboxControlFrame::GetContentInsert
   return mInRedisplayText ? mDisplayFrame : mDropdownFrame->GetContentInsertionFrame();
 }
 
 nsresult
 nsComboboxControlFrame::CreateAnonymousContent(nsTArray<ContentInfo>& aElements)
 {
   // The frames used to display the combo box and the button used to popup the dropdown list
   // are created through anonymous content. The dropdown list is not created through anonymous
-  // content because it's frame is initialized specifically for the drop-down case and it is placed
+  // content because its frame is initialized specifically for the drop-down case and it is placed
   // a special list referenced through NS_COMBO_FRAME_POPUP_LIST_INDEX to keep separate from the
   // layout of the display and button.
   //
   // Note: The value attribute of the display content is set when an item is selected in the dropdown list.
   // If the content specified below does not honor the value attribute than nothing will be displayed.
 
   // For now the content that is created corresponds to two input buttons. It would be better to create the
   // tag as something other than input, but then there isn't any way to create a button frame since it