Issue #2191 - Require implementation of gfxFont::GetScaledFont and remove unnecessary gfxPlatform::GetScaledFontForFont.

Backported from Mozilla bug 1385029.

gfx/thebes/gfxFcPlatformFontList.cpp

@@ -1103,6 +1103,20 @@ gfxFontconfigFont::~gfxFontconfigFont()
 {
 }
 
+already_AddRefed<ScaledFont>
+gfxFontconfigFont::GetScaledFont(mozilla::gfx::DrawTarget *aTarget)
+{
+    if (!mAzureScaledFont) {
+        mAzureScaledFont =
+            Factory::CreateScaledFontForFontconfigFont(GetCairoScaledFont(),
+                                                       GetPattern(),
+                                                       GetAdjustedSize());
+    }
+
+    RefPtr<ScaledFont> scaledFont(mAzureScaledFont);
+    return scaledFont.forget();
+}
+
 gfxFcPlatformFontList::gfxFcPlatformFontList()
     : mLocalNames(64)
     , mGenericMappings(32)