Broken references in Encrypted Media Extensions

[dontcallmedom-bot]

While crawling Encrypted Media Extensions, the following links to other specifications were detected as pointing to non-existing anchors, which should be fixed:

• [ ] https://heycam.github.io/webidl/#dfn-present
• [ ] https://www.w3.org/TR/secure-contexts/#secure-context

_{This issue was detected and reported semi-automatically by Strudy based on data collected in webref.}