Update WHATWG links to use HTTPS

Extracted this out of #5649

This commit was created with the following commands:

```
find . -iname "*.webidl" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```

```
find . -iname "*.rs" -type f -print0 | xargs -0 sed -i '' 's/http:\(.*\)whatwg.org/https:\1whatwg.org/g'
```

components/script/dom/webidls/File.webidl

@@ -12,4 +12,4 @@ interface File : Blob {
   readonly attribute DOMString name;
   // readonly attribute Date lastModifiedDate;
 
-};
+};