[threads][test][js-api] Add tests for memory buffer integrity

test/js-api/memory/integrity.any.js

@@ -0,0 +1,25 @@
+// META: global=window,dedicatedworker,jsshell
+
+test(() => {
+  const memory =
+      new WebAssembly.Memory({'initial': 1, 'maximum': 2, 'shared': true});
+  const buffer = memory.buffer;
+  assert_true(Object.isFrozen(buffer), 'Shared buffer should be frozen');
+  assert_throws_js(TypeError, () => {
+    'use strict';
+    buffer.x = 1;
+  }, 'Cannot add property to frozen shared buffer');
+}, 'Shared memory buffer integrity');
+
+test(() => {
+  const memory = new WebAssembly.Memory({'initial': 1});
+  const buffer = memory.buffer;
+  assert_false(
+      Object.isFrozen(buffer), 'Non-shared buffer should not be frozen');
+  assert_true(
+      Object.isExtensible(buffer), 'Non-shared buffer should be extensible');
+  buffer.x = 1;
+  assert_equals(
+      buffer.x, 1, 'Should be able to add property to non-shared buffer');
+  delete buffer.x;
+}, 'Non-shared memory buffer integrity');