Support iife heuristic in DDC

pkg/dev_compiler/lib/src/js_ast/nodes.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 js_ast;
 
 abstract class NodeVisitor<T> implements TypeRefVisitor<T> {
   T visitProgram(Program node);
 
   T visitBlock(Block node);
@@ skipping 1128 matching lines @@
 class Super extends Expression {
   accept(NodeVisitor visitor) => visitor.visitSuper(this);
   Super _clone() => new Super();
   int get precedenceLevel => PRIMARY;
   void visitChildren(NodeVisitor visitor) {}
 }
 
 class NamedFunction extends Expression {
   final Identifier name;
   final Fun function;
+  // A heuristic to force extra parens around this function.  V8 and other
+  // engines use this IIFE (immediately invoked function expression) heuristic
+  // to eagerly parse a function.
+  final bool immediatelyInvoked;
 
-  NamedFunction(this.name, this.function);
+  NamedFunction(this.name, this.function, [this.immediatelyInvoked = false]);
 
   accept(NodeVisitor visitor) => visitor.visitNamedFunction(this);
 
   void visitChildren(NodeVisitor visitor) {
     name.accept(visitor);
     function.accept(visitor);
   }
-  NamedFunction _clone() => new NamedFunction(name, function);
+  NamedFunction _clone() => new NamedFunction(name, function, immediatelyInvoked);
 
-  int get precedenceLevel => PRIMARY_LOW_PRECEDENCE;
+  int get precedenceLevel => immediatelyInvoked ? EXPRESSION : PRIMARY_LOW_PRECEDENCE;
 }
 
 abstract class FunctionExpression extends Expression {
   List<Parameter> get params;
 
   get body; // Expression or block
   /// Type parameters passed to this generic function, if any. `null` otherwise.
   // TODO(ochafik): Support type bounds.
   List<Identifier> get typeParams;
   /// Return type of this function, if any. `null` otherwise.
@@ skipping 695 matching lines @@
 
   final List<ModuleItem> body;
   Module(this.body, {this.name});
 
   accept(NodeVisitor visitor) => visitor.visitModule(this);
   void visitChildren(NodeVisitor visitor) {
     for (ModuleItem item in body) item.accept(visitor);
   }
   Module _clone() => new Module(body);
 }