Added Canvas#inspect()

lib/canvas.js

@@ -146,6 +146,17 @@ var parseColor = exports.parseColor = function(str){
   }
 };
 
+/**
+ * Inspect canvas.
+ *
+ * @return {String}
+ * @api public
+ */
+
+Canvas.prototype.inspect = function(){
+  return '[Canvas ' + this.width + ' ' + this.height + ']';
+};
+
 /**
  * Get a context object.
  *