Do not specify language for font fallback

Source/platform/exported/linux/WebFontInfo.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 43 matching lines @@
 
     FcValue fcvalue;
     fcvalue.type = FcTypeCharSet;
     fcvalue.u.c = cset;
     FcPatternAdd(pattern, FC_CHARSET, fcvalue, FcFalse);
 
     fcvalue.type = FcTypeBool;
     fcvalue.u.b = FcTrue;
     FcPatternAdd(pattern, FC_SCALABLE, fcvalue, FcFalse);
 
-    if (preferredLocale) {
+    if (preferredLocale && strlen(preferredLocale)) {
         FcLangSet* langset = FcLangSetCreate();
         FcLangSetAdd(langset, reinterpret_cast<const FcChar8 *>(preferredLocale));
         FcPatternAddLangSet(pattern, FC_LANG, langset);
         FcLangSetDestroy(langset);
     }
 
     FcConfigSubstitute(0, pattern, FcMatchPattern);
     FcDefaultSubstitute(pattern);
 
+    // Default substitution reintroduces an FC_LANG entry,
+    // which causes sorting order to change.
+    if (!preferredLocale || !strlen(preferredLocale))
+        FcPatternDel(pattern, FC_LANG);
+
     FcResult result;
     FcFontSet* fontSet = FcFontSort(0, pattern, 0, 0, &result);
     FcPatternDestroy(pattern);
     FcCharSetDestroy(cset);
 
     if (!fontSet) {
         fallbackFont->name = WebCString();
         fallbackFont->isBold = false;
         fallbackFont->isItalic = false;
         return;
@@ skipping 124 matching lines @@
     }
 
     // FontConfig doesn't provide parameters to configure whether subpixel
     // positioning should be used or not, so we just use a global setting.
     out->useSubpixelPositioning = useSubpixelPositioning;
 
     FcPatternDestroy(match);
 }
 
 } // namespace blink