dart2js cps: Make Identical a built-in and add Interceptor to Tree IR.

pkg/compiler/lib/src/js_backend/codegen/task.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.
 
 /// Generate code using the cps-based IR pipeline.
 library code_generator_task;
 
 import 'glue.dart';
 import 'codegen.dart';
 import 'unsugar.dart';
@@ skipping 13 matching lines @@
 import '../../tree_ir/tree_ir_builder.dart' as tree_builder;
 import '../../cps_ir/optimizers.dart';
 import '../../cps_ir/optimizers.dart' as cps_opt;
 import '../../tracer.dart';
 import '../../js_backend/codegen/codegen.dart';
 import '../../ssa/ssa.dart' as ssa;
 import '../../tree_ir/optimization/optimization.dart';
 import '../../tree_ir/optimization/optimization.dart' as tree_opt;
 import '../../tree_ir/tree_ir_integrity.dart';
 import '../../cps_ir/cps_ir_nodes_sexpr.dart';
-import 'js_tree_builder.dart';
 
 class CpsFunctionCompiler implements FunctionCompiler {
   final ConstantSystem constantSystem;
   final Compiler compiler;
   final Glue glue;
   final SourceInformationFactory sourceInformationFactory;
 
   // TODO(karlklose,sigurm): remove and update dart-doc of [compile].
   final FunctionCompiler fallbackCompiler;
 
@@ skipping 140 matching lines @@
     TypePropagator typePropagator = new TypePropagator(compiler);
     applyCpsPass(typePropagator);
     dumpTypedIR(cpsNode, typePropagator);
     applyCpsPass(new RedundantPhiEliminator());
     applyCpsPass(new ShrinkingReducer());
 
     return cpsNode;
   }
 
   tree_ir.FunctionDefinition compileToTreeIR(cps.FunctionDefinition cpsNode) {
-    tree_builder.Builder builder = new JsTreeBuilder(
-        compiler.internalError, compiler.identicalFunction, glue);
+    tree_builder.Builder builder = new tree_builder.Builder(
+        compiler.internalError);
     tree_ir.FunctionDefinition treeNode = builder.buildFunction(cpsNode);
     assert(treeNode != null);
     traceGraph('Tree builder', treeNode);
     assert(checkTreeIntegrity(treeNode));
     return treeNode;
   }
 
   static bool checkTreeIntegrity(tree_ir.FunctionDefinition node) {
     new CheckTreeIntegrity().check(node);
     return true; // So this can be used from assert().
@@ skipping 25 matching lines @@
     // TODO(sigurdm): Make a better list of tasks.
     return <CompilerTask>[irBuilderTask]..addAll(fallbackCompiler.tasks);
   }
 
   js.Node attachPosition(js.Node node, AstElement element) {
     return node.withSourceInformation(
         sourceInformationFactory.forContext(element)
             .buildDeclaration(element));
   }
 }