Implement CSS Emphasis Marks for complex text

Source/platform/fonts/harfbuzz/HarfBuzzShaper.h

Index: Source/platform/fonts/harfbuzz/HarfBuzzShaper.h
diff --git a/Source/platform/fonts/harfbuzz/HarfBuzzShaper.h b/Source/platform/fonts/harfbuzz/HarfBuzzShaper.h
index 461e2c9a3124eabd963011c05742392cb3af8a68..734c8aa711de280aad2f9e89dd06015623efa47e 100644
--- a/Source/platform/fonts/harfbuzz/HarfBuzzShaper.h
+++ b/Source/platform/fonts/harfbuzz/HarfBuzzShaper.h
@@ -53,7 +53,12 @@ public:
         NormalizeMirrorChars
     };
 
-    HarfBuzzShaper(const Font*, const TextRun&);
+    enum ForTextEmphasisOrNot {
+        NotForTextEmphasis,
+        ForTextEmphasis
+    };
+
+    HarfBuzzShaper(const Font*, const TextRun&, bool forTextEmphasis = false);
 
     void setDrawRange(int from, int to);
     bool shape(GlyphBuffer* = 0);
@@ -149,6 +154,8 @@ private:
     int m_fromIndex;
     int m_toIndex;
 
+    bool m_forTextEmphasis;
+
     float m_totalWidth;
 
     friend struct CachedShapingResults;