* Return allowed KSES tags if not an array

* Update PHPDoc to indicate a string param or return value is possible

…meo-shortocode-support

* 'develop' of github.com:ampproject/amp-wp: (159 commits)
  Return allowed KSES tags if not an array (#3879)
  Update dependency @wordpress/date to v3.6.0 (#3739)
  Update dependency @babel/plugin-proposal-object-rest-spread to… (#3813)
  Update dependency @babel/core to v7.7.4 (#3686)
  Update dependency @wordpress/api-fetch to v3.7.0 (#3731)
  Update dependency @wordpress/keycodes to v2.7.0 (#3745)
  Bundle common font files for externalizing data: URLs (#3866)
  Update dependency css-loader to v3.2.1 (#3870)
  Update dependency core-js to v3.4.7 (#3873)
  Update dependency core-js to v3.4.5 (#3695)
  Update dependency eslint-plugin-react to v7.17.0 (#3845)
  Update dependency eslint-plugin-jest to v23.1.1 (#3702)
  Update dependency eslint to v6.7.2 (#3811)
  Update dependency autoprefixer to v9.7.3 (#3850)
  Update dependency browserslist to v4.8.0 (#3849)
  Remove second sentence from paired browsing dialog
  Add async attribute to amp-paired-browsing-client script
  Restrict paired browsing to when dev mode is enabled
  Add robots noindex/nofollow meta tag in paired browsing app
  Remove extraneous method in favor of (temporary) closure
  ...

* tag '1.4.2': (25 commits)
  Bump 1.4.2
  Bump 'tested up to' to 5.3.2
  Catch unfiltered requests when testing Crowsignal embed (#3956)
  Bump version 1.4.2-RC1
  Bump 'Tested up to' to 5.3.1
  Remove test case for paired browsing since broken in WP4.9 and would not pass in AMP 1.4 (#3928)
  Further refine is_exclusively_dependent and add tests (#3928)
  Only include hoverintent-js in dev mode if exclusive dependency of admin-bar (#3928)
  Include admin-bar script deps in dev mode (e.g. hoverintent-js) (#3928)
  Fix tests after security fix in WP 5.3.1 (r46896) (#3926)
  Add E2E tests to allow_failures
  Convert `theme_features` variable into `get_theme_config` function
  Only apply smooth scroll fix on 'Twenty Twenty' <= 1.0.0
  Re-add smooth scrolling fix on WP < 5.3.1
  No need to apply smooth scrolling fix for Twenty Twenty theme
  Bump stylesheet cache group after #3866 (#3880)
  Return allowed KSES tags if not an array (#3879)
  Bundle common font files for externalizing data: URLs (#3866)
  Pull the built `block-libray` package from Gutenberg SVN if it does not exists (#3847)
  Optimize is_amp_allowed_attribute checking for reference points (#3815)
  ...