[blink] Support top-level await in synthetic modules

When top-level await is enabled, all module script evaluation is
expected to return a Promise. This CL changes
ValueWrapperSyntheticModuleScripts (CSS and JSON) to return a Promise
that's resolved to undefined.

Bug: v8:1154497
Change-Id: I92114d42f0080918e9e61bf1b62d5eda4cffdabc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568823
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833790}

third_party/blink/renderer/core/script/value_wrapper_synthetic_module_script.cc

@@ -4,6 +4,7 @@
 
 #include "third_party/blink/renderer/core/script/value_wrapper_synthetic_module_script.h"
 
+#include "third_party/blink/public/common/features.h"
 #include "third_party/blink/public/platform/web_vector.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_css_style_sheet_init.h"
@@ -199,7 +200,20 @@ v8::MaybeLocal<v8::Value> ValueWrapperSyntheticModuleScript::EvaluationSteps(
   DCHECK(!try_catch.HasCaught());
   DCHECK(!result.IsNothing() && result.FromJust());
 
-  return v8::Undefined(reinterpret_cast<v8::Isolate*>(isolate));
+  if (base::FeatureList::IsEnabled(features::kTopLevelAwait)) {
+    v8::Local<v8::Promise::Resolver> promise_resolver;
+    if (!v8::Promise::Resolver::New(context).ToLocal(&promise_resolver)) {
+      if (!isolate->IsExecutionTerminating()) {
+        LOG(FATAL) << "Cannot recover from failure to create a new "
+                      "v8::Promise::Resolver object (OOM?)";
+      }
+      return v8::MaybeLocal<v8::Value>();
+    }
+    promise_resolver->Resolve(context, v8::Undefined(isolate)).ToChecked();
+    return promise_resolver->GetPromise();
+  }
+
+  return v8::Undefined(isolate);
 }
 
 void ValueWrapperSyntheticModuleScript::Trace(Visitor* visitor) const {

third_party/blink/web_tests/TestExpectations

@@ -1592,6 +1592,7 @@ crbug.com/1022182 virtual/module-top-level-await/external/wpt/html/webappapis/dy
 crbug.com/1022182 virtual/module-top-level-await/external/wpt/html/webappapis/dynamic-markup-insertion/document-write/module-tla-immediate-promise.html [ Pass ]
 crbug.com/1022182 virtual/module-top-level-await/external/wpt/html/webappapis/dynamic-markup-insertion/document-write/module-tla-import.html [ Pass ]
 crbug.com/1022182 virtual/module-top-level-await/external/wpt/html/webappapis/dynamic-markup-insertion/document-write/module-tla-promise.html [ Pass ]
+crbug.com/1022182 virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/parse-error.tentative.html [ Skip ]
 
 crbug.com/1024331 external/wpt/css/css-text/hyphens/hyphens-out-of-flow-001.html [ Failure ]
 crbug.com/1024331 external/wpt/css/css-text/hyphens/hyphens-out-of-flow-002.html [ Failure ]

third_party/blink/web_tests/VirtualTestSuites

@@ -4,6 +4,7 @@
     "bases": [
       "external/wpt/html/webappapis/dynamic-markup-insertion/document-write",
       "external/wpt/html/semantics/scripting-1/the-script-element/module",
+      "external/wpt/html/semantics/scripting-1/the-script-element/json-module",
       "external/wpt/service-workers/service-worker/registration-script-module.https.html",
       "external/wpt/service-workers/service-worker/update-registration-with-type.https.html",
       "external/wpt/workers/Worker-terminate-forever-during-evaluation.html",
@@ -14,7 +15,7 @@
       "fast/loader/invalid-module-specifier.html",
       "http/tests/devtools/isolated-code-cache/"
     ],
-    "args": ["--enable-features=TopLevelAwait"]
+    "args": ["--enable-features=TopLevelAwait,JSONModules"]
   },
   {
     "prefix": "disable-accept-language-header",

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/json-module-service-worker-test.https.tentative-expected.txt

+This is a testharness.js-based test.
+PASS Javascript importing JSON Module should load within the context of a service worker
+PASS JSON Modules should load within the context of a service worker
+PASS JSON Module dynamic import should not load within the context of a service worker
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/module.tentative-expected.txt

+This is a testharness.js-based test.
+PASS JSON modules
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/non-object.tentative.any-expected.txt

+This is a testharness.js-based test.
+PASS Non-object: null
+PASS Non-object: true
+PASS Non-object: false
+PASS Non-object: string
+PASS Non-object: array
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/non-object.tentative.any.sharedworker-expected.txt

+This is a testharness.js-based test.
+PASS Non-object: null
+PASS Non-object: true
+PASS Non-object: false
+PASS Non-object: string
+PASS Non-object: array
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/non-object.tentative.any.worker-expected.txt

+This is a testharness.js-based test.
+PASS Non-object: null
+PASS Non-object: true
+PASS Non-object: false
+PASS Non-object: string
+PASS Non-object: array
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/utf8.tentative-expected.txt

+This is a testharness.js-based test.
+PASS utf-8
+PASS shift-jis
+PASS windows-1252
+PASS utf-7
+Harness: the test ran to completion.
+

third_party/blink/web_tests/virtual/module-top-level-await/external/wpt/html/semantics/scripting-1/the-script-element/json-module/valid-content-type.tentative-expected.txt

+This is a testharness.js-based test.
+PASS text/json
+PASS application/json
+FAIL text/html+json assert_unreached: [object Event] Reached unreachable code
+FAIL image/svg+json assert_unreached: [object Event] Reached unreachable code
+Harness: the test ran to completion.
+