Add setter to Isolate for allowing Atomics.wait

This makes it easier to set the value for embedders where it is
difficult to plumb through to the Isolate constructor.

BUG=chromium:711809
R=jochen@chromium.org

Review-Url: https://codereview.chromium.org/2829223002
Cr-Commit-Position: refs/heads/master@{#44813}

include/v8.h

@@ -6619,7 +6619,7 @@ class V8_EXPORT Isolate {
 
     /**
      * Whether calling Atomics.wait (a function that may block) is allowed in
-     * this isolate.
+     * this isolate. This can also be configured via SetAllowAtomicsWait.
      */
     bool allow_atomics_wait;
 
@@ -7479,6 +7479,13 @@ class V8_EXPORT Isolate {
    */
   bool IsInUse();
 
+  /**
+   * Set whether calling Atomics.wait (a function that may block) is allowed in
+   * this isolate. This can also be configured via
+   * CreateParams::allow_atomics_wait.
+   */
+  void SetAllowAtomicsWait(bool allow);
+
   Isolate() = delete;
   ~Isolate() = delete;
   Isolate(const Isolate&) = delete;

src/api.cc

@@ -8942,6 +8942,10 @@ void Isolate::VisitWeakHandles(PersistentHandleVisitor* visitor) {
   isolate->global_handles()->IterateWeakRootsInNewSpaceWithClassIds(visitor);
 }
 
+void Isolate::SetAllowAtomicsWait(bool allow) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  isolate->set_allow_atomics_wait(allow);
+}
 
 MicrotasksScope::MicrotasksScope(Isolate* isolate, MicrotasksScope::Type type)
     : isolate_(reinterpret_cast<i::Isolate*>(isolate)),

test/cctest/test-api.cc

@@ -26557,3 +26557,18 @@ TEST(DeterministicRandomNumberGeneration) {
 
   v8::internal::FLAG_random_seed = previous_seed;
 }
+
+UNINITIALIZED_TEST(AllowAtomicsWait) {
+  using namespace i;
+  v8::Isolate::CreateParams create_params;
+  create_params.allow_atomics_wait = false;
+  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
+  v8::Isolate* isolate = v8::Isolate::New(create_params);
+  Isolate* i_isolate = reinterpret_cast<Isolate*>(isolate);
+  {
+    CHECK_EQ(false, i_isolate->allow_atomics_wait());
+    isolate->SetAllowAtomicsWait(true);
+    CHECK_EQ(true, i_isolate->allow_atomics_wait());
+  }
+  isolate->Dispose();
+}