Bug 1471584 - Micro-optimize text shaping by avoiding an unnecessary virtual method call. r=lsalzman

gfx/thebes/gfxHarfBuzzShaper.cpp

@@ -57,7 +57,7 @@ gfxHarfBuzzShaper::gfxHarfBuzzShaper(gfxFont *aFont)
       mNumLongVMetrics(0),
       mDefaultVOrg(-1.0),
       mUseFontGetGlyph(aFont->ProvidesGetGlyph()),
-      mUseFontGlyphWidths(false),
+      mUseFontGlyphWidths(aFont->ProvidesGlyphWidths()),
       mInitialized(false),
       mVerticalInitialized(false),
       mLoadedLocaGlyf(false),
@@ -379,13 +379,13 @@ hb_position_t
 gfxHarfBuzzShaper::HBGetGlyphHAdvance(hb_font_t *font, void *font_data,
                                       hb_codepoint_t glyph, void *user_data)
 {
-    const gfxHarfBuzzShaper::FontCallbackData *fcd =
+    const gfxHarfBuzzShaper::FontCallbackData* fcd =
         static_cast<const gfxHarfBuzzShaper::FontCallbackData*>(font_data);
-    gfxFont *gfxfont = fcd->mShaper->GetFont();
-    if (gfxfont->ProvidesGlyphWidths()) {
-        return gfxfont->GetGlyphWidth(*fcd->mDrawTarget, glyph);
+    const gfxHarfBuzzShaper* shaper = fcd->mShaper;
+    if (shaper->mUseFontGlyphWidths) {
+        return shaper->GetFont()->GetGlyphWidth(*fcd->mDrawTarget, glyph);
     }
-    return fcd->mShaper->GetGlyphHAdvance(glyph);
+    return shaper->GetGlyphHAdvance(glyph);
 }
 
 /* static */
@@ -1211,8 +1211,6 @@ gfxHarfBuzzShaper::Initialize()
     mInitialized = true;
     mCallbackData.mShaper = this;
 
-    mUseFontGlyphWidths = mFont->ProvidesGlyphWidths();
-
     if (!sHBFontFuncs) {
         // static function callback pointers, initialized by the first
         // harfbuzz shaper used