Apply suggestion from @davidlehn on use of Object.fromEntries.

Author: gkellogg

lib/expand.js

@@ -518,15 +518,12 @@ async function _expandObject({
       // if framing, can be a default object, but need to expand
       // key to determine that
       if(_isObject(value)) {
-        const expandedValue = {};
-        for(const [k, v] of Object.entries(value)) {
-          const kk = _expandIri(typeScopedContext, k, {vocab: true});
-          const vv = _asArray(v).map(vvv =>
-            _expandIri(typeScopedContext, vvv, {base: true, vocab: true})
-          );
-          expandedValue[kk] = vv;
-        }
-        value = expandedValue;
+        value = Object.fromEntries(Object.entries(value).map(([k, v]) => [
+          _expandIri(typeScopedContext, k, {vocab: true}),
+          _asArray(v).map(vv =>
+            _expandIri(typeScopedContext, vv, {base: true, vocab: true})
+          )
+        ]));
       }
       _validateTypeValue(value, options.isFrame);
       _addValue(