Fix a crash of SRI when used with web workers

third_party/WebKit/LayoutTests/http/tests/security/subresourceIntegrity/resources/subresource-integrity-fetch-worker.js

+importScripts('/resources/testharness.js');
+console.log('hehehe');
+const url = '../call-success.js';
+const integrity = 'sha256-B0/62fJSJFrdjEFR9ba04m/D+LHQ+zG6PGcaR0Trpxg=';
+
+promise_test(() => {
+    return fetch(url).then(res => res.text()).then(text => {
+        assert_equals(text, 'success();\n');
+    });
+}, 'No integrity');
+
+promise_test(() => {
+    return fetch(url, {integrity: integrity}).then(res => {
+        return res.text();
+    }).then(text => {
+        assert_equals(text, 'success();\n');
+    });
+}, 'Good integrity');
+
+promise_test(() => {
+    return fetch(url, {integrity: 'sha256-deadbeaf'}).then(res => {
+        assert_unreached('the integrity check should fail');
+    }, () => {
+        // The integrity check should fail.
+    });
+}, 'Bad integrity');
+
+done();