Filter formats regressed and broke amp.dev output

[dgilman]

🐛 Bug Report

Current behavior

Take a look at amp-img for websites. The header "Set multiple source files for different screen resolutions" is present but there is no content under it.

If you take a look at the source in ampproject/amphtml you can see this section is wrapped in a [filter formats= directive. The code that parses the filter appears to have regressed and you aren't getting any output on any of the different format pages.

Expected behavior/code

Content from the md is shown in the browser

Reproduction procedure

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