dart2js: Fix minor indentation issues.

pkg/compiler/lib/src/use_unused_api.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.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 64 matching lines @@
   useCodeEmitterTask(null);
   useScript(null);
   useProgramBuilder(null);
   useSemanticVisitor();
   useTreeVisitors();
 }
 
 useApi(api.ReadStringFromUri uri) {
 }
 
-
-
 void useConstant(constants.ConstantValue constant,
                  constants.ConstantExpression expression,
                  constants.ConstructedConstantExpression constructedConstant,
                  constants.ConstantSystem cs,
                  constants.Environment env) {
   constant.isObject;
   cs.isBool(constant);
   constructedConstant.computeInstanceType();
   constructedConstant.computeInstanceFields();
   expression.evaluate(null, null);
@@ skipping 206 matching lines @@
 
 class TreeVisitor1 extends tree_ir.ExpressionVisitor1
                       with tree_ir.StatementVisitor1 {
   noSuchMethod(inv) {}
 }
 
 useTreeVisitors() {
   new TreeVisitor1().visitExpression(null, null);
   new TreeVisitor1().visitStatement(null, null);
 }