Cherry pick two CLs back to M39 to fix a bug

include/core/SkMatrix.h

Index: include/core/SkMatrix.h
diff --git a/include/core/SkMatrix.h b/include/core/SkMatrix.h
index 9f44bed9c4da20251ccb2053d3b9e2ce7dcec2ee..a65cd19f217985b022cddd1bb86aa42f5f2ffd41 100644
--- a/include/core/SkMatrix.h
+++ b/include/core/SkMatrix.h
@@ -60,6 +60,10 @@ public:
         return this->getType() == 0;
     }
 
+    bool isScaleTranslate() const {
+        return !(this->getType() & ~(kScale_Mask | kTranslate_Mask));
+    }
+
     /** Returns true if will map a rectangle to another rectangle. This can be
         true if the matrix is identity, scale-only, or rotates a multiple of
         90 degrees.