Change fallback font collection in HarfBuzzShaper

Source/platform/fonts/shaping/HarfBuzzShaper.h

Index: Source/platform/fonts/shaping/HarfBuzzShaper.h
diff --git a/Source/platform/fonts/shaping/HarfBuzzShaper.h b/Source/platform/fonts/shaping/HarfBuzzShaper.h
index 466d9da47c172225ea70ec3cc4ba567edaedbe55..89b451b2859583dcfd96d1a2e31e7c94a1123350 100644
--- a/Source/platform/fonts/shaping/HarfBuzzShaper.h
+++ b/Source/platform/fonts/shaping/HarfBuzzShaper.h
@@ -60,10 +60,7 @@ public:
     FloatRect bounds() { return m_glyphBoundingBox; }
     int offsetForPosition(float targetX);
     unsigned numCharacters() const { return m_numCharacters; }
-    const HashSet<const SimpleFontData*>* fallbackFonts() const
-    {
-        return &m_fallbackFonts;
-    }
+    void fallbackFonts(HashSet<const SimpleFontData*>*) const;
 
     static float fillGlyphBuffer(Vector<RefPtr<ShapeResult>>&,
         GlyphBuffer*, const TextRun&, unsigned from, unsigned to);
@@ -94,7 +91,7 @@ private:
     float m_width;
     FloatRect m_glyphBoundingBox;
     Vector<RunInfo*> m_runs;
-    HashSet<const SimpleFontData*> m_fallbackFonts;
+    const SimpleFontData* m_primaryFont;
 
     unsigned m_numCharacters;
     unsigned m_numGlyphs : 31;
@@ -109,8 +106,7 @@ private:
 
 class PLATFORM_EXPORT HarfBuzzShaper final : public Shaper {
 public:
-    HarfBuzzShaper(const Font*, const TextRun&,
-        HashSet<const SimpleFontData*>* fallbackFonts);
+    HarfBuzzShaper(const Font*, const TextRun&);
     PassRefPtr<ShapeResult> shapeResult();
     ~HarfBuzzShaper() { }