Change SetReverse to GetInverse in CFX_Matrix

CFX_Matrix::GetInverse is much clearer.
Change-Id: Id10ab1723735332e1a78de853f28415ec3a4d834
Reviewed-on: https://pdfium-review.googlesource.com/7090
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Nicolás Peña <npm@chromium.org>
diff --git a/fpdfsdk/formfiller/cffl_formfiller.cpp b/fpdfsdk/formfiller/cffl_formfiller.cpp
index 526f4b9..565d2ba 100644
--- a/fpdfsdk/formfiller/cffl_formfiller.cpp
+++ b/fpdfsdk/formfiller/cffl_formfiller.cpp
@@ -459,28 +459,19 @@
 }
 
 CFX_FloatRect CFFL_FormFiller::FFLtoPWL(const CFX_FloatRect& rect) {
-  CFX_Matrix mt;
-  mt.SetReverse(GetCurMatrix());
-
   CFX_FloatRect temp = rect;
-  mt.TransformRect(temp);
-
+  GetCurMatrix().GetInverse().TransformRect(temp);
   return temp;
 }
 
 CFX_FloatRect CFFL_FormFiller::PWLtoFFL(const CFX_FloatRect& rect) {
-  CFX_Matrix mt = GetCurMatrix();
-
   CFX_FloatRect temp = rect;
-  mt.TransformRect(temp);
-
+  GetCurMatrix().TransformRect(temp);
   return temp;
 }
 
 CFX_PointF CFFL_FormFiller::FFLtoPWL(const CFX_PointF& point) {
-  CFX_Matrix mt;
-  mt.SetReverse(GetCurMatrix());
-  return mt.Transform(point);
+  return GetCurMatrix().GetInverse().Transform(point);
 }
 
 CFX_PointF CFFL_FormFiller::PWLtoFFL(const CFX_PointF& point) {