Update request's referrer policy when fetching

With this change request's referrer policy is updated before calculating referrer so that the referrer policy actually used for the referrer calculation is transferred to the service worker and the default referrer policy is not transferred to the service worker.

Fixes #266.

Overview.html

@@ -7,7 +7,7 @@
 
 <p><a class="logo" href="https://whatwg.org/"><img alt="WHATWG" height="100" src="https://resources.whatwg.org/logo-fetch.svg" width="100"></a>
 <h1 id="cors">Fetch</h1>
-<h2 class="no-num no-toc" id="living-standard-—-last-updated-10-april-2016">Living Standard — Last Updated 10 April 2016</h2>
+<h2 class="no-num no-toc" id="living-standard-—-last-updated-13-april-2016">Living Standard — Last Updated 13 April 2016</h2>
 
 <dl>
  <dt>Participate:
@@ -2101,6 +2101,23 @@ <h3 id="main-fetch"><span class="secno">5.1 </span>Main fetch</h3>
  <a href="#refsMIX">[MIX]</a>
  <a href="#refsCSP">[CSP]</a>
 
+ <li><p>If <var>request</var>'s <a href="#concept-request-referrer-policy" title="concept-request-referrer-policy">referrer policy</a>
+ is the empty string and <var>request</var>'s
+ <a href="#concept-request-client" title="concept-request-client">client</a> is non-null, then set <var>request</var>'s
+ <a href="#concept-request-referrer-policy" title="concept-request-referrer-policy">referrer policy</a> to <var>request</var>'s
+ <a href="#concept-request-client" title="concept-request-client">client</a>'s
+ <a href="https://w3c.github.io/webappsec-referrer-policy/#referrer-policy">associated referrer policy</a>.
+ <a href="#refsREFERRER">[REFERRER]</a>
+
+ <li>
+  <p>If <var>request</var>'s <a href="#concept-request-referrer-policy" title="concept-request-referrer-policy">referrer policy</a>
+  is the empty string, then set <var>request</var>'s
+  <a href="#concept-request-referrer-policy" title="concept-request-referrer-policy">referrer policy</a> to
+  "<code>no-referrer-when-downgrade</code>".
+
+  <p class="note no-backref">We use "<code>no-referrer-when-downgrade</code>" because it is the
+  historical default.
+
  <li>
   <p>If <var>request</var>'s <a href="#concept-request-referrer" title="concept-request-referrer">referrer</a>
   is not "<code>no-referrer</code>", set <var>request</var>'s

Overview.src.html

@@ -2031,6 +2031,23 @@ <h3>Main fetch</h3>
  <span data-anolis-ref>MIX</span>
  <span data-anolis-ref>CSP</span>
 
+ <li><p>If <var>request</var>'s <span title=concept-request-referrer-policy>referrer policy</span>
+ is the empty string and <var>request</var>'s
+ <span title=concept-request-client>client</span> is non-null, then set <var>request</var>'s
+ <span title=concept-request-referrer-policy>referrer policy</span> to <var>request</var>'s
+ <span title=concept-request-client>client</span>'s
+ <a href="https://w3c.github.io/webappsec-referrer-policy/#referrer-policy">associated referrer policy</a>.
+ <span data-anolis-ref>REFERRER</span>
+
+ <li>
+  <p>If <var>request</var>'s <span title=concept-request-referrer-policy>referrer policy</span>
+  is the empty string, then set <var>request</var>'s
+  <span title=concept-request-referrer-policy>referrer policy</span> to
+  "<code>no-referrer-when-downgrade</code>".
+
+  <p class="note no-backref">We use "<code>no-referrer-when-downgrade</code>" because it is the
+  historical default.
+
  <li>
   <p>If <var>request</var>'s <span title=concept-request-referrer>referrer</span>
   is not "<code>no-referrer</code>", set <var>request</var>'s