Remove alt attribute from HTMLObjectElement interface

alt is not part of the HTML Standard for HTMLObjectElement

Fixes microsoft/TypeScript#21386

Author: benbraou

Diff for: baselines/dom.generated.d.ts

@@ -5960,10 +5960,6 @@ declare var HTMLModElement: {
 
 interface HTMLObjectElement extends HTMLElement, GetSVGDocument {
     align: string;
-    /**
-     * Sets or retrieves a text alternative to the graphic.
-     */
-    alt: string;
     /**
      * Gets or sets the optional alternative HTML script to execute if the object fails to load.
      */

Diff for: inputfiles/comments.json

@@ -2807,10 +2807,6 @@
             "name": "standby",
             "comment": "/**\r\n     * Sets or retrieves a message to be displayed while an object is loading.\r\n     */"
           },
-          {
-            "name": "alt",
-            "comment": "/**\r\n     * Sets or retrieves a text alternative to the graphic.\r\n     */"
-          },
           {
             "name": "classid",
             "comment": "/**\r\n     * Sets or retrieves the class identifier for the object.\r\n     */"

Diff for: inputfiles/removedTypes.json

@@ -83,5 +83,10 @@
     {
         "kind": "typedef",
         "name": "HeadersInit"
+    },
+    {
+        "kind": "property",
+        "interface": "HTMLObjectElement",
+        "name": "alt"
     }
 ]