Add missing `crossorigin` relevant mutations tests

This CL adds a few "missing" relevant mutations WPTs; specifically, it
exercises going from a valid state, to the state specified by the
invalid value default, by setting an img's `crossorigin` attribute to a
bogus value.

R=fs@opera.com, hiroshige@chromium.org

Bug: 1061685
Change-Id: I07166be176925693267c287fde53f4f09b3aeff8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2135542Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756271}

third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-img-element/relevant-mutations-expected.txt

 This is a testharness.js-based test.
-Found 81 tests; 74 PASS, 7 FAIL, 0 TIMEOUT, 0 NOTRUN.
+Found 83 tests; 76 PASS, 7 FAIL, 0 TIMEOUT, 0 NOTRUN.
 PASS src set
 PASS src changed
 PASS src removed
@@ -20,6 +20,7 @@ PASS crossorigin anonymous to use-credentials, src absent
 PASS crossorigin use-credentials to absent, src absent
 PASS crossorigin use-credentials to empty, src absent
 PASS crossorigin use-credentials to anonymous, src absent
+PASS crossorigin use-credentials to invalid, src absent
 PASS crossorigin absent to empty, src already set
 PASS crossorigin absent to anonymous, src already set
 PASS crossorigin absent to use-credentials, src already set
@@ -30,6 +31,7 @@ PASS crossorigin anonymous to use-credentials, src already set
 PASS crossorigin use-credentials to absent, src already set
 PASS crossorigin use-credentials to empty, src already set
 PASS crossorigin use-credentials to anonymous, src already set
+PASS crossorigin use-credentials to invalid, src already set
 FAIL inserted into picture assert_unreached: update the image data didn't run Reached unreachable code
 FAIL removed from picture assert_unreached: update the image data didn't run Reached unreachable code
 PASS parent is picture, previous source inserted

third_party/blink/web_tests/external/wpt/html/semantics/embedded-content/the-img-element/relevant-mutations.html

@@ -31,6 +31,7 @@
 <img crossorigin=use-credentials data-desc="crossorigin use-credentials to absent, src absent">
 <img crossorigin=use-credentials data-desc="crossorigin use-credentials to empty, src absent">
 <img crossorigin=use-credentials data-desc="crossorigin use-credentials to anonymous, src absent">
+<img crossorigin=use-credentials data-desc="crossorigin use-credentials to invalid, src absent">
 
 <img src="/images/green-2x2.png" data-desc="crossorigin absent to empty, src already set">
 <img src="/images/green-2x2.png" data-desc="crossorigin absent to anonymous, src already set">
@@ -42,6 +43,7 @@
 <img src="/images/green-2x2.png" crossorigin=use-credentials data-desc="crossorigin use-credentials to absent, src already set">
 <img src="/images/green-2x2.png" crossorigin=use-credentials data-desc="crossorigin use-credentials to empty, src already set">
 <img src="/images/green-2x2.png" crossorigin=use-credentials data-desc="crossorigin use-credentials to anonymous, src already set">
+<img src="/images/green-2x2.png" crossorigin=use-credentials data-desc="crossorigin use-credentials to invalid, src already set">
 
 <img src="/images/green-2x2.png" data-desc="inserted into picture"><picture></picture>
 
@@ -220,6 +222,10 @@ onload = function() {
     img.crossOrigin = 'anonymous';
   }, 'timeout');
 
+  t('crossorigin use-credentials to invalid, src absent', function(img) {
+    img.crossOrigin = 'foobar';
+  }, 'timeout');
+
   // When src is set, changing the crossorigin attribute state MUST generate
   // events.
 
@@ -263,6 +269,10 @@ onload = function() {
     img.crossOrigin = 'anonymous';
   }, 'load');
 
+  t('crossorigin use-credentials to invalid, src already set', function(img) {
+    img.crossOrigin = 'foobar';
+  }, 'load');
+
   t('inserted into picture', function(img) {
     img.nextSibling.appendChild(img);
   }, 'load');