Update the ORB spec to align with Firefox's implementation

fetch.bs

@@ -3328,8 +3328,7 @@ and a <a for=/>response</a> <var>response</var>, is to run these steps:
    <li><p>If <var>response</var>'s <a for=response>status</a> is 206 and <var>mimeType</var> is an
    <a>opaque-response-blocklisted MIME type</a>, then return false.
 
-   <li><p>If <var>nosniff</var> is true and <var>mimeType</var> is an
-   <a>opaque-response-blocklisted MIME type</a> or its <a for="MIME type">essence</a> is
+   <li><p>If <var>nosniff</var> is true and <var>mimeType</var>'s <a for="MIME type">essence</a> is
    "<code>text/plain</code>", then return false.
   </ol>
 
@@ -3461,6 +3460,7 @@ run these steps:</p>
 
 <hr>
 
+<div algorithm>
 <p>To <dfn>obtain a copy of the first 1024 bytes of response</dfn>, given a <a for=/>response</a>
 <var>response</var>, run these  steps:
 
@@ -3522,9 +3522,11 @@ run these steps:</p>
 
  <li>Return <var>first1024Bytes</var>.
 </ol>
+</div>
 
 <hr>
 
+<div algorithm>
 <p>To <dfn>determine if response is JavaScript and not JSON</dfn> given a <a for=/>response</a>
 <var>response</var>, run these steps:</p>
 
@@ -3580,6 +3582,7 @@ run these steps:</p>
 
  <li><p>Return false.
 </ol>
+</div>
 
 
 <h4 id=orb-mime-type-sets>New MIME type sets</h4>
@@ -3598,12 +3601,14 @@ run these steps:</p>
 whose <a for="MIME type">essence</a> is one of:
 
 <ul class=brief>
+ <li>"<code>application/dash+xml</code>"
  <li>"<code>application/gzip</code>"
  <li>"<code>application/msexcel</code>"
  <li>"<code>application/mspowerpoint</code>"
  <li>"<code>application/msword</code>"
  <li>"<code>application/msword-template</code>"
  <li>"<code>application/pdf</code>"
+ <li>"<code>application/vnd.apple.mpegurl</code>"
  <li>"<code>application/vnd.ces-quickpoint</code>"
  <li>"<code>application/vnd.ces-quicksheet</code>"
  <li>"<code>application/vnd.ces-quickword</code>"
@@ -3629,10 +3634,16 @@ whose <a for="MIME type">essence</a> is one of:
  <li>"<code>application/x-protobuf</code>"
  <li>"<code>application/x-protobuffer</code>"
  <li>"<code>application/zip</code>"
+ <li>"<code>audio/aac</code>"
+ <li>"<code>audio/aacp</code>"
+ <li>"<code>audio/mpegurl</code>"
+ <li>"<code>audio/mpeg</code>"
  <li>"<code>multipart/byteranges</code>"
  <li>"<code>multipart/signed</code>"
+ <li>"<code>multipart/x-mixed-replace</code>"
  <li>"<code>text/event-stream</code>"
  <li>"<code>text/csv</code>"
+ <li>"<code>text/vtt</code>"
 </ul>
 
 
@@ -5638,9 +5649,15 @@ these steps:
    <a>HTTP-network-or-cache fetch</a> given <var>fetchParams</var>.
 
    <li><p>If <var>request</var>'s <a for=request>response tainting</a> is "<code>opaque</code>",
-   <var>response</var>'s <a for=response>status</a> is not a <a>redirect status</a>, and the
-   <a>opaque-response-safelist check</a> given <var>request</var> and <var>response</var> returns
-   false, then return a <a>network error</a>.
+   <var>response</var>'s <a for=response>status</a> is not a <a>redirect status</a>, then
+
+   <ol>
+    <li><p>If <var>request</var>'s <a for=request>initiator type</a> is "<code>fetch</code>",
+    then set <var>internalResponse</var>'s <a for=response >body</a> to null.
+
+    <li><p>Otherwise, if <a>opaque-response-safelist check</a> given <var>request</var> and <var>response</var> returns
+    false, then return a <a>network error</a>.
+   </ol>
 
    <li><p>If <var>request</var>'s <a for=request>response tainting</a> is "<code>cors</code>" and
    the <a>CORS check</a> for <var>request</var> and <var>response</var> returns failure, then return