Reland 2: mac: Use a placeholder string for the family name of the system font.

Source/core/layout/LayoutThemeMac.h

Index: Source/core/layout/LayoutThemeMac.h
diff --git a/Source/core/layout/LayoutThemeMac.h b/Source/core/layout/LayoutThemeMac.h
index cba1b6fb7ea09bcdd90e3faccae1829d3c642bb1..982e2a5a627fcd7cba02cbda0add5949cc68b0fd 100644
--- a/Source/core/layout/LayoutThemeMac.h
+++ b/Source/core/layout/LayoutThemeMac.h
@@ -57,6 +57,8 @@ public:
     // System fonts.
     void systemFont(CSSValueID systemFontID, FontStyle&, FontWeight&, float& fontSize, AtomicString& fontFamily) const override;
 
+    bool needsHackForTextControlWithFontFamily(const AtomicString& family) const override;
+
     int minimumMenuListSize(const ComputedStyle&) const override;
 
     void adjustSliderThumbSize(ComputedStyle&) const override;