ServiceWorker: Update IDLs to use ScalarValueString

LayoutTests/http/tests/serviceworker/resources/request-worker.js

 importScripts('worker-test-helpers.js');
 
 test(function() {
     var headers = new HeaderMap;
     headers.set('User-Agent', 'Mozilla/5.0');
     headers.set('Accept', 'text/html');
     headers.set('X-ServiceWorker-Test', 'request test field');
 
     var request = new Request({
         url: 'https://www.example.com/test.html',
         method: 'GET',
         headers: headers
     });
 
     assert_equals(request.url, 'https://www.example.com/test.html', 'Request.url should match');
     assert_equals(request.method, 'GET', 'Request.method should match');
     assert_equals(request.origin, 'https://www.example.com', 'Request.origin should match');
     assert_true(request.headers instanceof HeaderMap, 'Request.headers should be HeaderMap');
     assert_equals(request.headers.size, 3, 'Request.headers.size should match');
     // Note: detailed behavioral tests for HeaderMap are in another test,
     // http/tests/serviceworker/headermap.html.
 
     request.url = 'http://localhost/';
     assert_equals(request.url, 'http://localhost/', 'Request.url should be writable');
+    request.url = 'http://localhost/\uD800'; // Unmatched lead surrogate.
+    assert_equals(request.url,
+                  'http://localhost/' + encodeURIComponent('\uFFFD'),
+                  'Request.url should have unmatched surrogates replaced.');
     request.method = 'POST';
     assert_equals(request.method, 'POST', 'Request.method should be writable');
     assert_throws({name: 'TypeError'}, function() { request.method = 'invalid \u0100'; },
                   'Request.method should throw on invalid ByteString');
 
 }, 'Request in ServiceWorkerGlobalScope');