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

pkg/compiler/lib/src/types/container_type_mask.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 types;
 
 /// A [ContainerTypeMask] is a [TypeMask] for a specific allocation
 /// site of a container (currently only List) that will get specialized
 /// once the [TypeGraphInferrer] phase finds an element type for it.
 class ContainerTypeMask extends ForwardingTypeMask {
@@ skipping 85 matching lines @@
 
   int get hashCode {
     return computeHashCode(
         allocationNode, isNullable, elementType, length, forwardTo);
   }
 
   String toString() {
     return 'Container mask: $elementType length: $length type: $forwardTo';
   }
 }