hide/remove obsolete/tricky SkMatrix methods

Change-Id: Iee399b929e8ca1a7326a326a643539d05e333d81
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/260818
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/src/gpu/GrPathProcessor.cpp b/src/gpu/GrPathProcessor.cpp
index f944e23..f7765e3 100644
--- a/src/gpu/GrPathProcessor.cpp
+++ b/src/gpu/GrPathProcessor.cpp
@@ -99,7 +99,7 @@
             } else {
                 m = GetTransformMatrix(transform, SkMatrix::I());
             }
-            if (fInstalledTransforms[t].fCurrentValue.cheapEqualTo(m)) {
+            if (SkMatrixPriv::CheapEqual(fInstalledTransforms[t].fCurrentValue, m)) {
                 continue;
             }
             fInstalledTransforms[t].fCurrentValue = m;