Address the remaining review comments on http://chromiumcodereview.appspot.com/9431029.

lib/compiler/implementation/ssa/nodes.dart

Index: lib/compiler/implementation/ssa/nodes.dart
diff --git a/lib/compiler/implementation/ssa/nodes.dart b/lib/compiler/implementation/ssa/nodes.dart
index 98a77c7d6a003583fa54f1bea60e67deac8b8f7a..3c06e48ab2bde4d7279c31fc35f7c0e7f561f07e 100644
--- a/lib/compiler/implementation/ssa/nodes.dart
+++ b/lib/compiler/implementation/ssa/nodes.dart
@@ -2181,10 +2181,10 @@ class HIndexAssign extends HInvokeStatic {
 }
 
 class HIs extends HInstruction {
-  final Type typeName;
+  final Type typeExpression;
   final bool nullOk;
 
-  HIs(this.typeName, HInstruction expression, [nullOk = false])
+  HIs(this.typeExpression, HInstruction expression, [nullOk = false])
     : this.nullOk = nullOk, super(<HInstruction>[expression]);
 
   HInstruction get expression() => inputs[0];
@@ -2193,7 +2193,7 @@ class HIs extends HInstruction {
 
   accept(HVisitor visitor) => visitor.visitIs(this);
 
-  toString() => "$expression is $typeName";
+  toString() => "$expression is $typeExpression";
 }