Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

pkg/compiler/lib/src/cps_ir/redundant_phi.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.
 
 part of dart2js.optimizers;
 
 /// Eliminate redundant phis from the given [FunctionDefinition].
 ///
 /// Phis in this case are [Continuations] together with corresponding
 /// [InvokeContinuation]s. A [Continuation] parameter at position i is redundant
@@ skipping 160 matching lines @@
 
   // Insert it just below the binding of definition.
   InteriorNode binding = definition.parent;
 
   letCont.body = binding.body;
   binding.body.parent = letCont;
 
   binding.body = letCont;
   letCont.parent = binding;
 }