WIP: Resource Timing integration

When response is a network error or body is fully read,
finalize and report the response.

Depends on whatwg/fetch#1185

See:
w3c/resource-timing#261
and w3c/resource-timing#252

Author: noamr

xhr.bs

@@ -960,6 +960,11 @@ return <a>this</a>'s <a>cross-origin credentials</a>.
   </ol>
 </ol>
 
+<p id=report-xhr-timing>To <dfn>report timing</dfn> for an {{XMLHttpRequest}} object <var>xhr</var>,
+<a href="https://github.com/whatwg/fetch/pull/1185">finalize and report timing</a> for
+<var>xhr</var>'s <a for=XMLHttpRequest>response</a>, <var>xhr</var>'s <a>relevant global object</a>
+and "xmlhttprequest".
+
 <p id=handle-response-end-of-file>To <dfn>handle response end-of-body</dfn> for an
 {{XMLHttpRequest}} object <var>xhr</var>, run these steps:
 
@@ -969,6 +974,8 @@ return <a>this</a>'s <a>cross-origin credentials</a>.
  <li><p>If <var>xhr</var>'s <a for=XMLHttpRequest>response</a> is a <a>network error</a>, then
  return.
 
+ <li><p><a for=/>Report timing</a> for <var>xhr</var>.
+
  <li><p>Let <var>transmitted</var> be <var>xhr</var>'s <a>received bytes</a>'s
  <a for="byte sequence">length</a>.
 
@@ -1008,8 +1015,13 @@ return <a>this</a>'s <a>cross-origin credentials</a>.
  <a event><code>abort</code></a>, and "{{AbortError!!exception}}" {{DOMException}}.
 
  <li><p>Otherwise, if <var>xhr</var>'s <a for=XMLHttpRequest>response</a>'s is a
- <a for=/>network error</a>, run the <a>request error steps</a> for <var>xhr</var>,
- <a event><code>error</code></a>, and "{{NetworkError!!exception}}" {{DOMException}}.
+ <a for=/>network error</a>, then perform the following steps:
+ <ol>
+  <li><p><a for=/>Report timing</a> for <var>xhr</var>.
+
+  <li><p>Run the <a>request error steps</a> for <var>xhr</var>,
+  <a event><code>error</code></a>, and "{{NetworkError!!exception}}" {{DOMException}}.
+ </ol>
 </ol>
 
 <p>The <dfn>request error steps</dfn> for an {{XMLHttpRequest}} object <var>xhr</var>,