Track fields which are known to be always set to integer constants

lib/compiler/implementation/ssa/nodes.dart

 // Copyright (c) 2011, 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.
 
 interface HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
   R visitBitOr(HBitOr node);
   R visitBitXor(HBitXor node);
@@ skipping 1786 matching lines @@
 
   toString() => 'literal: $constant';
   accept(HVisitor visitor) => visitor.visitConstant(this);
 
   HType get guaranteedType() => constantType;
 
   bool isConstant() => true;
   bool isConstantBoolean() => constant.isBool();
   bool isConstantNull() => constant.isNull();
   bool isConstantNumber() => constant.isNum();
+  bool isConstantInteger() => constant.isInt();
   bool isConstantString() => constant.isString();
   bool isConstantList() => constant.isList();
   bool isConstantMap() => constant.isMap();
   bool isConstantFalse() => constant.isFalse();
   bool isConstantTrue() => constant.isTrue();
 
   // Maybe avoid this if the literal is big?
   bool isCodeMotionInvariant() => true;
 }
 
@@ skipping 776 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);
 }