Convert addAttributesToSVGElement to item plugin (#1448)

"full" plugins prevents from possible optimisation. We need to migrate
all plugins to "perItem" type and later implement visitor plugin api to
allow state.

Author: TrySound

plugins/addAttributesToSVGElement.js

@@ -1,6 +1,8 @@
 'use strict';
 
-exports.type = 'full';
+const { closestByName } = require('../lib/xast.js');
+
+exports.type = 'perItem';
 
 exports.active = false;
 
@@ -50,30 +52,32 @@ plugins: [
  *
  * @author April Arcus
  */
-exports.fn = function (data, params) {
-  if (!params || !(Array.isArray(params.attributes) || params.attribute)) {
-    console.error(ENOCLS);
-    return data;
-  }
+exports.fn = (node, params) => {
+  if (
+    node.type === 'element' &&
+    node.name === 'svg' &&
+    closestByName(node.parentNode, 'svg') == null
+  ) {
+    if (!params || !(Array.isArray(params.attributes) || params.attribute)) {
+      console.error(ENOCLS);
+      return;
+    }
 
-  var attributes = params.attributes || [params.attribute],
-    svg = data.children[0];
+    const attributes = params.attributes || [params.attribute];
 
-  if (svg.isElem('svg')) {
-    attributes.forEach(function (attribute) {
+    for (const attribute of attributes) {
       if (typeof attribute === 'string') {
-        if (svg.attributes[attribute] == null) {
-          svg.attributes[attribute] = undefined;
+        if (node.attributes[attribute] == null) {
+          node.attributes[attribute] = undefined;
         }
-      } else if (typeof attribute === 'object') {
-        Object.keys(attribute).forEach(function (key) {
-          if (svg.attributes[key] == null) {
-            svg.attributes[key] = attribute[key];
+      }
+      if (typeof attribute === 'object') {
+        for (const key of Object.keys(attribute)) {
+          if (node.attributes[key] == null) {
+            node.attributes[key] = attribute[key];
           }
-        });
+        }
       }
-    });
+    }
   }
-
-  return data;
 };