add SkCanvas constructor that explicitly creates no_config with dimensions

src/utils/SkNWayCanvas.cpp

Index: src/utils/SkNWayCanvas.cpp
diff --git a/src/utils/SkNWayCanvas.cpp b/src/utils/SkNWayCanvas.cpp
index da8bdb6f41cf7271e31b3a12942f8d9349f15f9d..831d7bf6cf122da4194931b1f28e5bd4cb1bd43c 100644
--- a/src/utils/SkNWayCanvas.cpp
+++ b/src/utils/SkNWayCanvas.cpp
@@ -7,14 +7,8 @@
  */
 #include "SkNWayCanvas.h"
 
-static SkBitmap make_noconfig_bm(int width, int height) {
-    SkBitmap bm;
-    bm.setConfig(SkBitmap::kNo_Config, width, height);
-    return bm;
-}
-
 SkNWayCanvas::SkNWayCanvas(int width, int height)
-        : INHERITED(make_noconfig_bm(width, height)) {}
+        : INHERITED(width, height) {}
 
 SkNWayCanvas::~SkNWayCanvas() {
     this->removeAll();