Add a type kind to TypedSelector. A typed selector can either be

sdk/lib/_internal/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.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
@@ skipping 1134 matching lines @@
   }
 
 
   HInstruction convertType(Compiler compiler, DartType type, int kind) {
     if (type == null) return this;
     if (identical(type.element, compiler.dynamicClass)) return this;
     if (identical(type.element, compiler.objectClass)) return this;
 
     // If the original can't be null, type conversion also can't produce null.
     bool canBeNull = this.guaranteedType.canBeNull();
-    HType convertedType =
-        new HType.fromBoundedType(type, compiler, canBeNull);
+    HType convertedType = new HType.subtype(type, compiler);
 
     // No need to convert if we know the instruction has
     // [convertedType] as a bound.
     if (this.guaranteedType == convertedType) {
       return this;
     }
 
     return new HTypeConversion(convertedType, this, kind);
   }
 
@@ skipping 1128 matching lines @@
 
   int typeCode() => HInstruction.IS_TYPECODE;
   bool typeEquals(HInstruction other) => other is HIs;
   bool dataEquals(HIs other) {
     return typeExpression == other.typeExpression
         && nullOk == other.nullOk;
   }
 }
 
 class HTypeConversion extends HCheck {
-  HType type;
+  final HType type;
   final int kind;
 
   static const int NO_CHECK = 0;
   static const int CHECKED_MODE_CHECK = 1;
   static const int ARGUMENT_TYPE_CHECK = 2;
   static const int CAST_TYPE_CHECK = 3;
   static const int BOOLEAN_CONVERSION_CHECK = 4;
 
   HTypeConversion(this.type, HInstruction input, [this.kind = NO_CHECK])
       : super(<HInstruction>[input]) {
+    assert(type != null);
     sourceElement = input.sourceElement;
   }
   HTypeConversion.checkedModeCheck(HType type, HInstruction input)
       : this(type, input, CHECKED_MODE_CHECK);
   HTypeConversion.argumentTypeCheck(HType type, HInstruction input)
       : this(type, input, ARGUMENT_TYPE_CHECK);
   HTypeConversion.castCheck(HType type, HInstruction input)
       : this(type, input, CAST_TYPE_CHECK);
 
 
@@ skipping 376 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);
 }