Fix drawVertices documentation

lib/ui/painting.dart

@@ -5442,8 +5442,8 @@ abstract class Canvas {
   /// specified in the `vertices` using the `blendMode` parameter. For the
   /// purposes of this blending, the colors from the `paint` parameter are
   /// considered the source, and the colors from the `vertices` are considered
-  /// the destination. [BlendMode.dstOver] ignores the `paint` and uses only the
-  /// colors of the `vertices`; [BlendMode.srcOver] ignores the colors of the
+  /// the destination. [BlendMode.dst] ignores the `paint` and uses only the
+  /// colors of the `vertices`; [BlendMode.src] ignores the colors of the
   /// `vertices` and uses only the colors in the `paint`.
   ///
   /// All parameters must not be null.