Worker: Add [Replaceable] to SharedWorkerGlobalScope.name

The HTML spec requires SharedWorkerGlobalScope.name has [Replaceable]:
https://html.spec.whatwg.org/multipage/workers.html#shared-workers-and-the-sharedworkerglobalscope-interface

This CL also fixes a test expectation of
wpt/workers/interfaces/SharedWorkerGlobalScope/name/setting.html. The name
attribute is now replaceable, so the result should be replaced. Firefox fails
the test because of this wrong expectation:
https://wpt.fyi/results/workers/interfaces/SharedWorkerGlobalScope/name/setting.html?label=stable&aligned&q=%2Fname%2Fsetting.html

Bug: 875714
Change-Id: Id04ae30895a2de4a07e30f49dc1189bb9742f6b9
Reviewed-on: https://chromium-review.googlesource.com/c/1347962Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610383}

third_party/WebKit/LayoutTests/external/wpt/workers/interfaces/SharedWorkerGlobalScope/name/setting.html

@@ -14,7 +14,7 @@ addEventListener('connect', function(e) {
 async_test(function() {
   var w1 = new SharedWorker('#1', 'x');
   w1.port.addEventListener('message', this.step_func(function(e) {
-    assert_equals(e.data, 'x');
+    assert_equals(e.data, 1);
     this.done();
   }), false);
   w1.port.start();

third_party/WebKit/LayoutTests/external/wpt/workers/name-property-expected.txt

@@ -3,7 +3,7 @@ PASS name property value for DedicatedWorkerGlobalScope
 PASS name property is replaceable for DedicatedWorkerGlobalScope
 PASS Declaring name as an accidental global must not cause a harness error for DedicatedWorkerGlobalScope
 FAIL name property value for SharedWorkerGlobalScope assert_equals: expected "my name" but got "[object Object]"
-FAIL name property is replaceable for SharedWorkerGlobalScope Cannot assign to read only property 'name' of object '#<SharedWorkerGlobalScope>'
-FAIL name-as-accidental-global Uncaught TypeError: Cannot assign to read only property 'name' of object '#<SharedWorkerGlobalScope>'
+PASS name property is replaceable for SharedWorkerGlobalScope
+PASS Declaring name as an accidental global must not cause a harness error for SharedWorkerGlobalScope
 Harness: the test ran to completion.
 

third_party/WebKit/LayoutTests/external/wpt/workers/support/name.js

@@ -2,8 +2,8 @@
 importScripts("/resources/testharness.js");
 
 test(() => {
-  assert_true(self.hasOwnProperty("name"), "property exists on the global")
-  assert_equals(self.name, "my name")
+  assert_true(self.hasOwnProperty("name"), "property exists on the global");
+  assert_equals(self.name, "my name");
 }, `name property value for ${self.constructor.name}`);
 
 test(() => {

third_party/WebKit/LayoutTests/virtual/stable/webexposed/global-interface-listing-shared-worker-expected.txt

@@ -2491,6 +2491,7 @@ Starting worker: resources/global-interface-listing-worker.js
 [Worker]     method webkitRequestFileSystemSync
 [Worker]     method webkitResolveLocalFileSystemSyncURL
 [Worker]     method webkitResolveLocalFileSystemURL
+[Worker]     setter name
 [Worker]     setter onconnect
 PASS successfullyParsed is true
 

third_party/WebKit/LayoutTests/webexposed/global-interface-listing-shared-worker-expected.txt

@@ -3461,6 +3461,7 @@ Starting worker: resources/global-interface-listing-worker.js
 [Worker]     method webkitRequestFileSystemSync
 [Worker]     method webkitResolveLocalFileSystemSyncURL
 [Worker]     method webkitResolveLocalFileSystemURL
+[Worker]     setter name
 [Worker]     setter onconnect
 PASS successfullyParsed is true
 

third_party/blink/renderer/core/workers/shared_worker_global_scope.idl

@@ -34,7 +34,7 @@
     Global=(Worker,SharedWorker),
     Exposed=SharedWorker
 ] interface SharedWorkerGlobalScope : WorkerGlobalScope {
-    readonly attribute DOMString name;
+    [Replaceable] readonly attribute DOMString name;
     // TODO(foolip): readonly attribute ApplicationCache applicationCache;
 
     void close();