fix(g-svg): autoDraw should be true and immutable, close #191

Author: dengfuping

packages/g-svg/src/canvas.ts

@@ -10,7 +10,10 @@ import Defs from './defs';
 
 class Canvas extends AbstractCanvas {
   constructor(cfg) {
-    super(cfg);
+    super({
+      ...cfg,
+      autoDraw: true,
+    });
   }
 
   /**