--- a/layout/generic/nsLineBox.cpp
+++ b/layout/generic/nsLineBox.cpp
@@ -198,18 +198,18 @@ ListFloats(FILE* out, const char* aPrefi
     else {
       str += "\n###!!! NULL out-of-flow frame";
     }
     fprintf_stderr(out, "%s\n", str.get());
     fc = fc->Next();
   }
 }
 
-const char*
-nsLineBox::BreakTypeToString(StyleClear aBreakType) const
+/* static */ const char*
+nsLineBox::BreakTypeToString(StyleClear aBreakType)
 {
   switch (aBreakType) {
     case StyleClear::None: return "nobr";
     case StyleClear::Left: return "leftbr";
     case StyleClear::Right: return "rightbr";
     case StyleClear::InlineStart: return "inlinestartbr";
     case StyleClear::InlineEnd: return "inlineendbr";
     case StyleClear::Both: return "leftbr+rightbr";

--- a/layout/generic/nsLineBox.h
+++ b/layout/generic/nsLineBox.h
@@ -569,17 +569,17 @@ public:
   // list).
   static bool RFindLineContaining(nsIFrame* aFrame,
                                     const nsLineList_iterator& aBegin,
                                     nsLineList_iterator& aEnd,
                                     nsIFrame* aLastFrameBeforeEnd,
                                     int32_t* aFrameIndexInLine);
 
 #ifdef DEBUG_FRAME_DUMP
-  const char* BreakTypeToString(StyleClear aBreakType) const;
+  static const char* BreakTypeToString(StyleClear aBreakType);
   char* StateToString(char* aBuf, int32_t aBufSize) const;
 
   void List(FILE* out, int32_t aIndent, uint32_t aFlags = 0) const;
   void List(FILE* out = stderr, const char* aPrefix = "", uint32_t aFlags = 0) const;
   nsIFrame* LastChild() const;
 #endif
 
 private: