cps-ir: Implement boolean conversion in and use it to implement '&&', '||', and '?:'.

pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart

 // Copyright (c) 2014, 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.
 
 library tree_ir_nodes;
 
 import '../constants/expressions.dart';
 import '../constants/values.dart' as values;
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import '../dart_types.dart' show DartType, GenericType;
@@ skipping 524 matching lines @@
   S visitReturn(Return node);
   S visitBreak(Break node);
   S visitContinue(Continue node);
   S visitIf(If node);
   S visitWhileTrue(WhileTrue node);
   S visitWhileCondition(WhileCondition node);
   S visitFunctionDeclaration(FunctionDeclaration node);
   S visitExpressionStatement(ExpressionStatement node);
 }
 
-abstract class Visitor<S,E> implements ExpressionVisitor<E>,
-                                       StatementVisitor<S> {
+abstract class Visitor<S, E> implements ExpressionVisitor<E>,
+                                        StatementVisitor<S> {
    E visitExpression(Expression e) => e.accept(this);
    S visitStatement(Statement s) => s.accept(this);
 }
 
 class RecursiveVisitor extends Visitor {
   visitFunctionDefinition(FunctionDefinition node) {
     visitStatement(node.body);
   }
 
   visitVariable(Variable node) {}
@@ skipping 97 matching lines @@
   visitFunctionDeclaration(FunctionDeclaration node) {
     visitFunctionDefinition(node.definition);
     visitStatement(node.next);
   }
 
   visitExpressionStatement(ExpressionStatement node) {
     visitExpression(node.expression);
     visitStatement(node.next);
   }
 }