a === b -> identical(a, b)

sdk/lib/_internal/compiler/implementation/dart_backend/placeholder_collector.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart_backend;
 
 class LocalPlaceholder {
   final String identifier;
   final Set<Node> nodes;
   LocalPlaceholder(this.identifier) : nodes = new Set<Node>();
@@ skipping 57 matching lines @@
 
   visitClosureSend(Send node) {
     final element = elements[node];
     if (element != null) {
       collector.tryMakeLocalPlaceholder(element, node.selector);
     }
   }
 
   visitGetterSend(Send node) {
     final element = elements[node];
-    // element === null means dynamic property access.
+    // element == null means dynamic property access.
     if (element == null) {
       collector.tryMakeMemberPlaceholder(node.selector);
     } else if (element.isErroneous()) {
       return;
     } else if (element.isPrefix()) {
       // Node is prefix part in case of source 'lib.somesetter = 5;'
       collector.makeNullPlaceholder(node);
     } else if (Elements.isStaticOrTopLevel(element)) {
       // Unqualified or prefixed top level or static.
       collector.makeElementPlaceholder(node.selector, element);
@@ skipping 115 matching lines @@
     this.topmostEnclosingFunction = null;
     final ElementAst elementAst = elementAsts[element];
     this.treeElements = elementAst.treeElements;
     Node elementNode = elementAst.ast;
     if (element is FunctionElement) {
       collectFunctionDeclarationPlaceholders(element, elementNode);
     } else if (element is VariableListElement) {
       VariableDefinitions definitions = elementNode;
       for (Node definition in definitions.definitions) {
         final definitionElement = treeElements[definition];
-        // definitionElement === null if variable is actually unused.
+        // definitionElement == null if variable is actually unused.
         if (definitionElement == null) continue;
         collectFieldDeclarationPlaceholders(definitionElement, definition);
       }
       makeVarDeclarationTypePlaceholder(definitions);
     } else {
       assert(element is ClassElement || element is TypedefElement);
     }
     currentLocalPlaceholders = new Map<String, LocalPlaceholder>();
     compiler.withCurrentElement(element, () {
       elementNode.accept(this);
@@ skipping 380 matching lines @@
 
   visitBlock(Block node) {
     for (Node statement in node.statements.nodes) {
       if (statement is VariableDefinitions) {
         makeVarDeclarationTypePlaceholder(statement);
       }
     }
     node.visitChildren(this);
   }
 }