Remove const form of CPDF_RenderContext::Layer::GetObjectHolder()

Only the non-const form is used.

Change-Id: Ic9463baae25c869cb7331991316499746d5f6eb9
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/99954
Commit-Queue: Lei Zhang <thestig@chromium.org>
Auto-Submit: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fpdfapi/render/cpdf_rendercontext.h b/core/fpdfapi/render/cpdf_rendercontext.h
index ae73b97..e61b974 100644
--- a/core/fpdfapi/render/cpdf_rendercontext.h
+++ b/core/fpdfapi/render/cpdf_rendercontext.h
@@ -32,9 +32,6 @@
     ~Layer();
 
     CPDF_PageObjectHolder* GetObjectHolder() { return m_pObjectHolder.Get(); }
-    const CPDF_PageObjectHolder* GetObjectHolder() const {
-      return m_pObjectHolder.Get();
-    }
     const CFX_Matrix& GetMatrix() const { return m_Matrix; }
 
    private: