Remove CSP plugin-types blocking

With Flash not being supported anymore, the CSP directive plugin-types has lost its main reason for being and is being removed from the Content Security Policy specification: w3c/webappsec-csp#456.

This change removes references to the relevant algorithm from the Content Security Policy spec.

source

@@ -3867,7 +3867,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li>The <dfn data-x-href="https://w3c.github.io/webappsec-csp/#allow-base-for-document">Is base allowed for Document?</dfn> algorithm</li>
      <li>The <dfn data-x-href="https://w3c.github.io/webappsec-csp/#frame-ancestors"><code data-x="">frame-ancestors</code> directive</dfn></li>
      <li>The <dfn data-x-href="https://w3c.github.io/webappsec-csp/#sandbox"><code data-x="">sandbox</code> directive</dfn></li>
-     <li>The <dfn data-x-href="https://w3c.github.io/webappsec-csp/#should-plugin-element-be-blocked-a-priori-by-content-security-policy">Should plugin element be blocked <i lang="la">a priori</i> by Content Security Policy?</dfn> algorithm</li>
      <li>The <dfn data-x-href="https://w3c.github.io/webappsec-csp/#contains-a-header-delivered-content-security-policy">contains a header-delivered Content Security Policy</dfn> property.</li>
     </ul>
    </dd>
@@ -30880,10 +30879,6 @@ interface <dfn>HTMLEmbedElement</dfn> : <span>HTMLElement</span> {
    <li><p>If another <span data-x="concept-task">task</span> has since been queued to run <span>the
    <code>embed</code> element setup steps</span> for <var>element</var>, then return.</p></li>
 
-   <li><p>If the <span>Should plugin element be blocked <i lang="la">a priori</i> by Content
-   Security Policy?</span> algorithm returns "<code data-x="">Blocked</code>" when executed on
-   <var>element</var>, then return. <ref spec=CSP></p></li>
-
    <li>
     <p>If <var>element</var> has a <code data-x="attr-embed-src">src</code> attribute set, then:</p>
 
@@ -31303,18 +31298,13 @@ interface <dfn>HTMLObjectElement</dfn> : <span>HTMLElement</span> {
     be shown because that content uses a format that the user finds more accessible.</p>
    </li>
 
-   <li>
-    <p>If the element has an ancestor <span>media element</span>, or has an ancestor
-    <code>object</code> element that is <em>not</em> showing its <span>fallback content</span>, or
-    if the element is not <span>in a document</span> whose <span
-    data-x="concept-document-bc">browsing context</span> is non-null, or if the element's <span>node
-    document</span> is not <span>fully active</span>, or if the element is still in the <span>stack
-    of open elements</span> of an <span>HTML parser</span> or <span>XML parser</span>, or if the
-    element is not <span>being rendered</span>, or if the <span>Should plugin element be blocked
-    <i lang="la">a priori</i> by Content Security Policy?</span> algorithm returns "<code
-    data-x="">Blocked</code>" when executed on the element, then jump to the step below labeled
-    <i>fallback</i>. <ref spec=CSP></p>
-   </li>
+   <li><p>If the element has an ancestor <span>media element</span>, or has an ancestor
+   <code>object</code> element that is <em>not</em> showing its <span>fallback content</span>, or if
+   the element is not <span>in a document</span> whose <span data-x="concept-document-bc">browsing
+   context</span> is non-null, or if the element's <span>node document</span> is not <span>fully
+   active</span>, or if the element is still in the <span>stack of open elements</span> of an
+   <span>HTML parser</span> or <span>XML parser</span>, or if the element is not <span>being
+   rendered</span>, then jump to the step below labeled <i>fallback</i>.</p></li>
 
    <li>
     <!-- what if it's not in the document? if that should prevent plugin instantiation, then here
@@ -123198,6 +123188,7 @@ INSERT INTERFACES HERE
   Anthony Ramine,
   Anthony Ricaud,
   Anton Vayvod,
+  Antonio Sartori,
   Antti Koivisto,
   Arfat Salman,
   Arkadiusz Michalski,