Disallow streaming upload on HTTP/1.x connections

This is to reduce the risk to break existing HTTP/1.1 servers.

Fixes #966.

Author: yutakahirano

fetch.bs

@@ -5447,11 +5447,9 @@ optional boolean <var>forceNewConnection</var> (default false), run these steps:
    <a for="fetch timing info">post-redirect start time</a>, and <var>fetchParams</var>'s
    <a for="fetch params">cross-origin isolated capability</a>.
 
-   <li><p>If <var>connection</var> is not an HTTP/2 connection, <var>request</var>'s
+   <li><p>If <var>connection</var> is an HTTP/1.x connection, <var>request</var>'s
    <a for=request>body</a> is non-null, and <var>request</var>'s <a for=request>body</a>'s
-   <a for=body>source</a> is null, then <a for="header list">append</a>
-   (`<code>Transfer-Encoding</code>`, `<code>chunked</code>`) to <var>request</var>'s
-   <a for=request>header list</a>.
+   <a for=body>source</a> is null, then return a <a>network error</a>.
 
    <li>Set <var>timingInfo</var>'s <a for="fetch timing info">final network-request start time</a>
    to the <a for=/>coarsened shared current time</a> given <var>fetchParams</var>'s
@@ -5525,10 +5523,6 @@ optional boolean <var>forceNewConnection</var> (default false), run these steps:
     therefore <var>response</var> represents both a <a for=/>response</a> and
     an HTTP response here.
 
-    <p>If <var>request</var>'s <a for=request>header list</a> contains
-    (`<code>Transfer-Encoding</code>`, `<code>chunked</code>`) and <var>response</var> is
-    transferred via HTTP/1.0 or older, then return a <a>network error</a>.
-
     <p>If the HTTP request results in a TLS client certificate dialog, then:
 
     <ol>