Improve type safety of name global variable

Author: falsandtru

TS.fsx

@@ -924,7 +924,7 @@ module Emit =
 
             // Treat window.name specially because of https://github.com/Microsoft/TypeScript/issues/9850
             if p.Name = "name" && i.Name = "Window" && emitScope = EmitScope.All then
-                printLine "declare const name: never;"
+                printLine "declare const name: string | undefined;"
             elif Option.isNone (getRemovedItemByName p.Name ItemKind.Property i.Name) then
                 match getOverriddenItemByName p.Name ItemKind.Property i.Name with
                 | Some p' -> emitPropertyFromJson p'

baselines/dom.generated.d.ts

@@ -14734,7 +14734,7 @@ declare var locationbar: BarProp;
 declare var menubar: BarProp;
 declare var msContentScript: ExtensionScriptApis;
 declare var msCredentials: MSCredentials;
-declare const name: never;
+declare const name: string | undefined;
 declare var navigator: Navigator;
 declare var offscreenBuffering: string | boolean;
 declare var onabort: (this: Window, ev: UIEvent) => any;