Add http method to fetch timing info

This change will allow for the addition of
the http method to the resource-timing spec

Explainer: https://github.com/rt-explainer
Associated resource-timing PR: w3c/resource-timing#375

fetch.bs

@@ -353,6 +353,8 @@ following <a for=struct>items</a>: [[RESOURCE-TIMING]] [[NAVIGATION-TIMING]]
  <dd>A <a for=/>list</a> of strings.
  <dt><dfn export for="fetch timing info">render-blocking</dfn> (default false)
  <dd>A boolean.
+ <dt><dfn export for="fetch timing info">http method</dfn> (default: GET)
+ <dd> A {{ByteString}}
 </dl>
 
 <p>A <dfn export>response body info</dfn> is a <a for=/>struct</a> used to maintain
@@ -4231,7 +4233,9 @@ the response. [[!HTTP-CACHING]]
  <li><p>Let <var>timingInfo</var> be a new <a for=/>fetch timing info</a> whose
  <a for="fetch timing info">start time</a> and
  <a for="fetch timing info">post-redirect start time</a> are the
- <a for=/>coarsened shared current time</a> given <var>crossOriginIsolatedCapability</var>, and
+ <a for=/>coarsened shared current time</a> given <var>crossOriginIsolatedCapability</var>,
+ <a for="fetch timing info">http method</a> is set to <var>request</var>'s
+ <a for=request>method</a>, and
  <a for="fetch timing info">render-blocking</a> is set to <var>request</var>'s
  <a for=request>render-blocking</a>.