Revert[2] "remove SK_SUPPORT_LEGACY_CLIP_REGIONOPS"

This reverts commit a129dfef2aaab0b5995cdf1ab7b2cdd41c29cf72.

BUG=skia:

Change-Id: I717de6e5fcd4516aa684b014b1414b0f82ac2b91
Reviewed-on: https://skia-review.googlesource.com/5722
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
diff --git a/tests/ReadPixelsTest.cpp b/tests/ReadPixelsTest.cpp
index 1550c6d..71cd8f5 100644
--- a/tests/ReadPixelsTest.cpp
+++ b/tests/ReadPixelsTest.cpp
@@ -111,7 +111,7 @@
 static void fill_src_canvas(SkCanvas* canvas) {
     canvas->save();
     canvas->setMatrix(SkMatrix::I());
-    canvas->clipRect(DEV_RECT_S, SkCanvas::kReplace_Op);
+    canvas->clipRect(DEV_RECT_S, kReplace_SkClipOp);
     SkPaint paint;
     paint.setBlendMode(SkBlendMode::kSrc);
     canvas->drawBitmap(make_src_bitmap(), 0, 0, &paint);