Make -webkit-font-variant-ligatures actually work.

Source/platform/fonts/harfbuzz/HarfBuzzShaper.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 BlackBerry Limited. 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.
@@ skipping 503 matching lines @@
     case FontDescription::NormalKerning:
         // kern/vkrn are enabled by default
         break;
     case FontDescription::NoneKerning:
         m_features.append(description.orientation() == Vertical ? noVkrn : noKern);
         break;
     case FontDescription::AutoKerning:
         break;
     }
 
+    static hb_feature_t noClig = { HB_TAG('c', 'l', 'i', 'g'), 0, 0, static_cast<unsigned>(-1) };
+    static hb_feature_t noLiga = { HB_TAG('l', 'i', 'g', 'a'), 0, 0, static_cast<unsigned>(-1) };
+    switch (description.commonLigaturesState()) {
+    case FontDescription::DisabledLigaturesState:
+        m_features.append(noLiga);
+        m_features.append(noClig);
+        break;
+    case FontDescription::EnabledLigaturesState:
+        // liga and clig are on by default
+        break;
+    case FontDescription::NormalLigaturesState:
+        break;
+    }
+    static hb_feature_t dlig = { HB_TAG('d', 'l', 'i', 'g'), 1, 0, static_cast<unsigned>(-1) };
+    switch (description.discretionaryLigaturesState()) {
+    case FontDescription::DisabledLigaturesState:
+        // dlig is off by default
+        break;
+    case FontDescription::EnabledLigaturesState:
+        m_features.append(dlig);
+        break;
+    case FontDescription::NormalLigaturesState:
+        break;
+    }
+    static hb_feature_t hlig = { HB_TAG('h', 'l', 'i', 'g'), 1, 0, static_cast<unsigned>(-1) };
+    switch (description.historicalLigaturesState()) {
+    case FontDescription::DisabledLigaturesState:
+        // hlig is off by default
+        break;
+    case FontDescription::EnabledLigaturesState:
+        m_features.append(hlig);
+        break;
+    case FontDescription::NormalLigaturesState:
+        break;
+    }
+
     FontFeatureSettings* settings = description.featureSettings();
     if (!settings)
         return;
 
     unsigned numFeatures = settings->size();
     for (unsigned i = 0; i < numFeatures; ++i) {
         hb_feature_t feature;
         const AtomicString& tag = settings->at(i).tag();
         feature.tag = HB_TAG(tag[0], tag[1], tag[2], tag[3]);
         feature.value = settings->at(i).value();
@@ skipping 495 matching lines @@
     if (!foundToX)
         toX = m_run.rtl() ? 0 : m_totalWidth;
 
     // Using floorf() and roundf() as the same as mac port.
     if (fromX < toX)
         return FloatRect(floorf(point.x() + fromX), point.y(), roundf(toX - fromX), height);
     return FloatRect(floorf(point.x() + toX), point.y(), roundf(fromX - toX), height);
 }
 
 } // namespace WebCore