Enable strong mode in DDC, fix all warnings/errors

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 827 matching lines @@
   BindingPattern(this.variables);
 
   void visitChildren(NodeVisitor visitor) {
     for (DestructuredVariable v in variables) v.accept(visitor);
   }
 }
 
 class SimpleBindingPattern extends BindingPattern {
   final Identifier name;
   SimpleBindingPattern(Identifier name)
-      : super([new DestructuredVariable(name: name)]), this.name = name;
+      : name = name,
+        super([new DestructuredVariable(name: name)]);
+
   accept(NodeVisitor visitor) => visitor.visitSimpleBindingPattern(this);
 
   /// Avoid parenthesis when pretty-printing.
   @override int get precedenceLevel => PRIMARY;
   @override Node _clone() => new SimpleBindingPattern(name);
 }
 
 class ObjectBindingPattern extends BindingPattern {
   ObjectBindingPattern(List<DestructuredVariable> variables)
       : super(variables);
@@ skipping 98 matching lines @@
     return new Block([left.toStatement(), right.toReturn()]);
   }
 
   Statement toYieldStatement({bool star: false}) {
     if (!isCommaOperator) return super.toYieldStatement(star: star);
     return new Block([left.toStatement(), right.toYieldStatement(star: star)]);
   }
 
   List<Expression> commaToExpressionList() {
     if (!isCommaOperator) throw new StateError('not a comma expression');
-    var exprs = [];
+    var exprs = <Expression>[];
     _flattenComma(exprs, left);
     _flattenComma(exprs, right);
     return exprs;
   }
 
   static void _flattenComma(List<Expression> exprs, Expression node) {
     if (node is Binary && node.isCommaOperator) {
       _flattenComma(exprs, node.left);
       _flattenComma(exprs, node.right);
     } else {
@@ skipping 884 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);
 }