The GetFont method of nsIFontMetrics takes a const pointer reference

as argument, so we must pass a const pointer reference to it.

gfx/src/gtk/nsRenderingContextGTK.cpp

@@ -903,7 +903,7 @@ nsRenderingContextGTK::DrawString(const char *aString, PRUint32 aLength,
 
   if (mFontMetrics)
   {
-    nsFont *font;
+    const nsFont *font;
     mFontMetrics->GetFont(font);
     PRUint8 deco = font->decorations;