Remove unimplemented CFX_FontMgr::ReleaseFace().

Stray declaration of a method removed at 3512b96d

Change-Id: I2257884b590284fc0b398a1294a218dd3e5c443b
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/56390
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/core/fxge/cfx_fontmgr.h b/core/fxge/cfx_fontmgr.h
index 18fe9ad..3498ea1 100644
--- a/core/fxge/cfx_fontmgr.h
+++ b/core/fxge/cfx_fontmgr.h
@@ -54,7 +54,6 @@
       int font_offset);
   RetainPtr<CFX_Face> GetFixedFace(pdfium::span<const uint8_t> span,
                                    int face_index);
-  void ReleaseFace(RetainPtr<CFX_Face> face);
   void SetSystemFontInfo(std::unique_ptr<SystemFontInfoIface> pFontInfo);
   RetainPtr<CFX_Face> FindSubstFont(const ByteString& face_name,
                                     bool bTrueType,