Fix crash when using disallowed URLs in image sets for content CSS property

third_party/WebKit/LayoutTests/fast/css/content-image-set-disallowed-url-crash.html

Index: third_party/WebKit/LayoutTests/fast/css/content-image-set-disallowed-url-crash.html
diff --git a/third_party/WebKit/LayoutTests/fast/css/content-image-set-disallowed-url-crash.html b/third_party/WebKit/LayoutTests/fast/css/content-image-set-disallowed-url-crash.html
new file mode 100644
index 0000000000000000000000000000000000000000..f57b6ff6a49dfbaa69254af792709cc89675f75b
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/fast/css/content-image-set-disallowed-url-crash.html
@@ -0,0 +1,16 @@
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+
+<style>
+#target {
+  content: -webkit-image-set(url("chrome://disallowed-url/") 1x);
+}
+</style>
+
+<img id="target"></img>
+
+<script>
+test(() => {
+  console.log(getComputedStyle(target).content);
+}, 'This test passes if it does not crash.');
+</script>