Migrate std docs index to Map

See also rust-lang/rust#118910

Author: Folyd

extension/index/std-docs.js

@@ -72,12 +72,17 @@ class DocSearch {
     }
 
     buildIndex(rawSearchIndex) {
+        if (!rawSearchIndex) {
+            // if the rawSearchIndex is undefined or null, give it a empty map
+            // to call iterate.
+            rawSearchIndex = new Map();
+        } else if (rawSearchIndex instanceof Object) {
+            rawSearchIndex = Object.entries(rawSearchIndex);
+        }
         let searchIndex = [];
         const searchWords = [];
         const charA = "A".charCodeAt(0);
-        // if the rawSearchIndex is undefined or null, give it a empty object `{}`
-        // to call iterate.
-        for (let [crateName, indexItem] of Object.entries(rawSearchIndex || {})) {
+        for (let [crateName, indexItem] of rawSearchIndex) {
             searchWords.push(crateName);
             searchIndex.push({
                 crate: crateName,