Stop using the Hashable interface.

lib/compiler/implementation/ssa/nodes.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.
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
@@ skipping 414 matching lines @@
   bool contains(HInstruction instruction) {
     HInstruction cursor = first;
     while (cursor != null) {
       if (cursor === instruction) return true;
       cursor = cursor.next;
     }
     return false;
   }
 }
 
-class HBasicBlock extends HInstructionList implements Hashable {
+class HBasicBlock extends HInstructionList  {
   // The [id] must be such that any successor's id is greater than
   // this [id]. The exception are back-edges.
   int id;
 
   static const int STATUS_NEW = 0;
   static const int STATUS_OPEN = 1;
   static const int STATUS_CLOSED = 2;
   int status = STATUS_NEW;
 
   HInstructionList phis;
@@ skipping 286 matching lines @@
   bool dominates(HBasicBlock other) {
     do {
       if (this === other) return true;
       other = other.dominator;
     } while (other !== null && other.id >= id);
     return false;
   }
 }
 
 
-class HInstruction implements Hashable, Spannable {
+class HInstruction implements Spannable {
   Element sourceElement;
   SourceFileLocation sourcePosition;
 
   final int id;
   static int idCounter;
 
   final List<HInstruction> inputs;
   final List<HInstruction> usedBy;
 
   HBasicBlock block;
@@ skipping 2151 matching lines @@
   HBasicBlock get start => expression.start;
   HBasicBlock get end {
     // We don't create a switch block if there are no cases.
     assert(!statements.isEmpty());
     return statements.last().end;
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
       visitor.visitSwitchInfo(this);
 }