title: Array.includes always return false
body: <p>I have an Object in the Arrays 0' th element as follows,</p>
  
  <pre><code>Array = {CreatedById: "Created By ID",CreatedDate: "Created Date",Id: 
  "Record ID",IsDeleted: "Deleted",LastActivityDate: "Last Activity 
  Date",LastModifiedById: "Last Modified By ID",LastModifiedDate: "Last 
  Modified Date",Name: "Data Import Name",OwnerId: "Owner ID",SystemModstamp: 
  "System Modstamp",Last_Name__c: "Last Name",Mandate_Date_Signed__c: "Mandate 
  Date Signed",Mandate_End_Date__c: "Mandate End Date",Mandate__c: "Mandate"}
  </code></pre>
  
  <p>I'll need to check whether a key is available in the above array. I have used the <code>includes()</code> function like <code>Array.includes('Last Name')</code>. But it always return <code>false</code>. Did I miss anything? I'll need to check the key in the whole array even in key or value. Any modification to check the key in the <code>Object</code>?</p>