Import latest WritableStream tests from upstream

third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/byte-length-queuing-strategy.js

Index: third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/byte-length-queuing-strategy.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/byte-length-queuing-strategy.js b/third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/byte-length-queuing-strategy.js
new file mode 100644
index 0000000000000000000000000000000000000000..611689f88171390ba22c4d2cf40be293d1478b2d
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/http/tests/streams/writable-streams/byte-length-queuing-strategy.js
@@ -0,0 +1,33 @@
+'use strict';
+
+if (self.importScripts) {
+  self.importScripts('/resources/testharness.js');
+}
+
+promise_test(() => {
+  let isDone = false;
+  const ws = new WritableStream(
+    {
+      write() {
+        return new Promise(resolve => {
+          setTimeout(() => {
+            isDone = true;
+            resolve();
+          }, 200);
+        });
+      },
+
+      close() {
+        assert_true(isDone, 'close is only called once the promise has been resolved');
+      }
+    },
+    new ByteLengthQueuingStrategy({ highWaterMark: 1024 * 16 })
+  );
+
+  const writer = ws.getWriter();
+  writer.write({ byteLength: 1024 });
+
+  return writer.close();
+}, 'Closing a writable stream with in-flight writes below the high water mark delays the close call properly');
+
+done();