bootstrap: stop delaying instantiation of maps in per-context scripts

The linked issue, https://bugs.chromium.org/p/v8/issues/detail?id=6593,
is marked as "Fixed", so I think we can revert this now.

This reverts commit 08a9c4a.

Signed-off-by: Darshan Sen <raisinten@gmail.com>

PR-URL: #42934
Refs: https://bugs.chromium.org/p/v8/issues/detail?id=9187
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

lib/internal/per_context/domexception.js

@@ -36,37 +36,18 @@ function throwInvalidThisError(Base, type) {
   throw err;
 }
 
-let disusedNamesSet;
-let internalsMap;
-let nameToCodeMap;
-let isInitialized = false;
+const internalsMap = new SafeWeakMap();
+const nameToCodeMap = new SafeMap();
 
-// We need to instantiate the maps lazily because they render
-// the snapshot non-rehashable.
-// https://bugs.chromium.org/p/v8/issues/detail?id=6593
-function ensureInitialized() {
-  if (isInitialized) {
-    return;
-  }
-  internalsMap = new SafeWeakMap();
-  nameToCodeMap = new SafeMap();
-  forEachCode((name, codeName, value) => {
-    nameToCodeMap.set(name, value);
-  });
-
-  // These were removed from the error names table.
-  // See https://github.com/heycam/webidl/pull/946.
-  disusedNamesSet = new SafeSet()
-    .add('DOMStringSizeError')
-    .add('NoDataAllowedError')
-    .add('ValidationError');
-
-  isInitialized = true;
-}
+// These were removed from the error names table.
+// See https://github.com/heycam/webidl/pull/946.
+const disusedNamesSet = new SafeSet()
+  .add('DOMStringSizeError')
+  .add('NoDataAllowedError')
+  .add('ValidationError');
 
 class DOMException {
   constructor(message = '', name = 'Error') {
-    ensureInitialized();
     ErrorCaptureStackTrace(this);
     internalsMap.set(this, {
       message: `${message}`,
@@ -75,7 +56,6 @@ class DOMException {
   }
 
   get name() {
-    ensureInitialized();
     const internals = internalsMap.get(this);
     if (internals === undefined) {
       throwInvalidThisError(TypeError, 'DOMException');
@@ -84,7 +64,6 @@ class DOMException {
   }
 
   get message() {
-    ensureInitialized();
     const internals = internalsMap.get(this);
     if (internals === undefined) {
       throwInvalidThisError(TypeError, 'DOMException');
@@ -93,7 +72,6 @@ class DOMException {
   }
 
   get code() {
-    ensureInitialized();
     const internals = internalsMap.get(this);
     if (internals === undefined) {
       throwInvalidThisError(TypeError, 'DOMException');
@@ -116,40 +94,39 @@ ObjectDefineProperties(DOMException.prototype, {
   code: { enumerable: true, configurable: true }
 });
 
-function forEachCode(fn) {
-  fn('IndexSizeError', 'INDEX_SIZE_ERR', 1);
-  fn('DOMStringSizeError', 'DOMSTRING_SIZE_ERR', 2);
-  fn('HierarchyRequestError', 'HIERARCHY_REQUEST_ERR', 3);
-  fn('WrongDocumentError', 'WRONG_DOCUMENT_ERR', 4);
-  fn('InvalidCharacterError', 'INVALID_CHARACTER_ERR', 5);
-  fn('NoDataAllowedError', 'NO_DATA_ALLOWED_ERR', 6);
-  fn('NoModificationAllowedError', 'NO_MODIFICATION_ALLOWED_ERR', 7);
-  fn('NotFoundError', 'NOT_FOUND_ERR', 8);
-  fn('NotSupportedError', 'NOT_SUPPORTED_ERR', 9);
-  fn('InUseAttributeError', 'INUSE_ATTRIBUTE_ERR', 10);
-  fn('InvalidStateError', 'INVALID_STATE_ERR', 11);
-  fn('SyntaxError', 'SYNTAX_ERR', 12);
-  fn('InvalidModificationError', 'INVALID_MODIFICATION_ERR', 13);
-  fn('NamespaceError', 'NAMESPACE_ERR', 14);
-  fn('InvalidAccessError', 'INVALID_ACCESS_ERR', 15);
-  fn('ValidationError', 'VALIDATION_ERR', 16);
-  fn('TypeMismatchError', 'TYPE_MISMATCH_ERR', 17);
-  fn('SecurityError', 'SECURITY_ERR', 18);
-  fn('NetworkError', 'NETWORK_ERR', 19);
-  fn('AbortError', 'ABORT_ERR', 20);
-  fn('URLMismatchError', 'URL_MISMATCH_ERR', 21);
-  fn('QuotaExceededError', 'QUOTA_EXCEEDED_ERR', 22);
-  fn('TimeoutError', 'TIMEOUT_ERR', 23);
-  fn('InvalidNodeTypeError', 'INVALID_NODE_TYPE_ERR', 24);
-  fn('DataCloneError', 'DATA_CLONE_ERR', 25);
+for (const { 0: name, 1: codeName, 2: value } of [
+  ['IndexSizeError', 'INDEX_SIZE_ERR', 1],
+  ['DOMStringSizeError', 'DOMSTRING_SIZE_ERR', 2],
+  ['HierarchyRequestError', 'HIERARCHY_REQUEST_ERR', 3],
+  ['WrongDocumentError', 'WRONG_DOCUMENT_ERR', 4],
+  ['InvalidCharacterError', 'INVALID_CHARACTER_ERR', 5],
+  ['NoDataAllowedError', 'NO_DATA_ALLOWED_ERR', 6],
+  ['NoModificationAllowedError', 'NO_MODIFICATION_ALLOWED_ERR', 7],
+  ['NotFoundError', 'NOT_FOUND_ERR', 8],
+  ['NotSupportedError', 'NOT_SUPPORTED_ERR', 9],
+  ['InUseAttributeError', 'INUSE_ATTRIBUTE_ERR', 10],
+  ['InvalidStateError', 'INVALID_STATE_ERR', 11],
+  ['SyntaxError', 'SYNTAX_ERR', 12],
+  ['InvalidModificationError', 'INVALID_MODIFICATION_ERR', 13],
+  ['NamespaceError', 'NAMESPACE_ERR', 14],
+  ['InvalidAccessError', 'INVALID_ACCESS_ERR', 15],
+  ['ValidationError', 'VALIDATION_ERR', 16],
+  ['TypeMismatchError', 'TYPE_MISMATCH_ERR', 17],
+  ['SecurityError', 'SECURITY_ERR', 18],
+  ['NetworkError', 'NETWORK_ERR', 19],
+  ['AbortError', 'ABORT_ERR', 20],
+  ['URLMismatchError', 'URL_MISMATCH_ERR', 21],
+  ['QuotaExceededError', 'QUOTA_EXCEEDED_ERR', 22],
+  ['TimeoutError', 'TIMEOUT_ERR', 23],
+  ['InvalidNodeTypeError', 'INVALID_NODE_TYPE_ERR', 24],
+  ['DataCloneError', 'DATA_CLONE_ERR', 25],
   // There are some more error names, but since they don't have codes assigned,
   // we don't need to care about them.
-}
-
-forEachCode((name, codeName, value) => {
+]) {
   const desc = { enumerable: true, value };
   ObjectDefineProperty(DOMException, codeName, desc);
   ObjectDefineProperty(DOMException.prototype, codeName, desc);
-});
+  nameToCodeMap.set(name, value);
+}
 
 exports.DOMException = DOMException;