Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-fallback-iframe.html

Index: third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-fallback-iframe.html
diff --git a/third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-fallback-iframe.html b/third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-fallback-iframe.html
new file mode 100644
index 0000000000000000000000000000000000000000..f00d24e37a8270cf65c0322c2dabb5d1a20910d2
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/fetch-request-fallback-iframe.html
@@ -0,0 +1,15 @@
+<script>
+function xhr(url) {
+  return new Promise(function(resolve, reject) {
+      var request = new XMLHttpRequest();
+      request.addEventListener(
+        'error',
+        function(event) { reject(event); });
+      request.addEventListener(
+        'load',
+        function(event) { resolve(request.response); });
+      request.open('GET', url);
+      request.send();
+    });
+}
+</script>