[Devtools] Update test for image previews

This cl adds the tests for crrev.com/c/1944331.

Fixed: 1029489
Change-Id: I35214f184a1ef53ea8f17b74923f48bd76200102
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1943142
Commit-Queue: Jan Scheffler <janscheffler@chromium.org>
Reviewed-by: Tim van der Lippe <tvanderlippe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720487}

third_party/blink/web_tests/http/tests/devtools/elements/elements-linkify-attributes-expected.txt

@@ -49,3 +49,9 @@ Link at offset: 46: data:​,def
 Rendered text: <a id=​"linkify-14" href=​"http:​/​/​www.google.com">​a link​</a>​
 Link at offset: 27: http:​/​/​www.google.com
 
+Rendered text: <image id=​"linkify-15" xlink:href=​"./​kitten-small.png" height=​"200" width=​"200">​</image>​
+Link at offset: 37: ./​kitten-small.png
+
+Rendered text: <image id=​"linkify-16" href=​"./​kitten-small.png" height=​"200" width=​"200">​</image>​
+Link at offset: 31: ./​kitten-small.png
+

third_party/blink/web_tests/http/tests/devtools/elements/elements-linkify-attributes.js

@@ -23,10 +23,15 @@
           <img id="linkify-13" srcset="data:,abc 1x,data:,def 2x">
       </picture>
       <a id="linkify-14" href="http://www.google.com">a link</a>
+      <svg width="200" height="200"
+        xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+        <image id="linkify-15" xlink:href="./kitten-small.png" height="200" width="200"/>
+        <image id="linkify-16" href="./kitten-small.png" height="200" width="200"/>
+      </svg>
     `);
 
   var i = 0;
-  var last = 14;
+  var last = 16;
 
   function check() {
     i++;