Fix a wrong variable check in CFX_BilinearMatrix.

This has existed since the initial PDFium check in.

BUG=chromium:805881

Change-Id: I34b79d61c753d15d0f112c12f3dee43973403673
Reviewed-on: https://pdfium-review.googlesource.com/24090
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxge/dib/cfx_imagetransformer.cpp b/core/fxge/dib/cfx_imagetransformer.cpp
index 37e2be0..e514153 100644
--- a/core/fxge/dib/cfx_imagetransformer.cpp
+++ b/core/fxge/dib/cfx_imagetransformer.cpp
@@ -192,7 +192,7 @@
     *res_y = static_cast<int>(fmodf(val.second, kBase));
     if (*res_x < 0 && *res_x > -kBase)
       *res_x = kBase + *res_x;
-    if (*res_y < 0 && *res_x > -kBase)
+    if (*res_y < 0 && *res_y > -kBase)
       *res_y = kBase + *res_y;
   }
 };