Bug 1575495: part 3) Sync argument names of declaration and definition of `DoAddText`. r=hsivonen

Differential Revision: https://phabricator.services.mozilla.com/D42839

--HG--
extra : moz-landing-system : lando

dom/base/nsPlainTextSerializer.h

@@ -108,7 +108,9 @@ class nsPlainTextSerializer final : public nsIContentSerializer {
   nsresult DoOpenContainer(nsAtom* aTag);
   nsresult DoCloseContainer(nsAtom* aTag);
   nsresult DoAddLeaf(nsAtom* aTag);
-  void DoAddText(bool aIsWhitespace, const nsAString& aText);
+
+  // @param aText Ignored if aIsLineBreak is true.
+  void DoAddText(bool aIsLineBreak, const nsAString& aText);
 
   // Inlined functions
   inline bool MayWrap() {