Fix typo in CFX_ImageTransformer::Continue

This CL fixes a typo introduced in:
https://pdfium-review.googlesource.com/c/4495/3/core/fxge/dib/cfx_imagetransformer.cpp#395

Bug: chromium:723976
Change-Id: I629d1e61054805f768356fce44c25f40f9346beb
Reviewed-on: https://pdfium-review.googlesource.com/5634
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Nicolás Peña <npm@chromium.org>
diff --git a/core/fxge/dib/cfx_imagetransformer.cpp b/core/fxge/dib/cfx_imagetransformer.cpp
index 11f5f56..6174a51 100644
--- a/core/fxge/dib/cfx_imagetransformer.cpp
+++ b/core/fxge/dib/cfx_imagetransformer.cpp
@@ -390,7 +390,7 @@
   }
   if (m_Storer.GetBitmap()->IsAlphaMask()) {
     if (!(m_Flags & FXDIB_DOWNSAMPLE) && !(m_Flags & FXDIB_BICUBIC_INTERPOL)) {
-      CFX_BilinearMatrix result2stretch_fix(result2stretch, 16);
+      CFX_BilinearMatrix result2stretch_fix(result2stretch, 8);
       for (int row = 0; row < m_result.Height(); row++) {
         uint8_t* dest_scan = (uint8_t*)pTransformed->GetScanline(row);
         for (int col = 0; col < m_result.Width(); col++) {