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

pkg/compiler/lib/src/ssa/invoke_dynamic_specializers.dart

 // Copyright (c) 2013, 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 ssa;
 
 /**
  * [InvokeDynamicSpecializer] and its subclasses are helpers to
  * optimize intercepted dynamic calls. It knows what input types
  * would be beneficial for performance, and how to change a invoke
@@ skipping 729 matching lines @@
     return constantSystem.codeUnitAt;
   }
 
   HInstruction tryConvertToBuiltin(HInvokeDynamic instruction,
                                    Compiler compiler) {
     // TODO(sra): Implement a builtin HCodeUnitAt instruction and the same index
     // bounds checking optimizations as for HIndex.
     return null;
   }
 }