[kernel] Change how TypeParameterType is calculated.

pkg/kernel/lib/binary/ast_to_binary.dart

Index: pkg/kernel/lib/binary/ast_to_binary.dart
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index 27cfbeed41c708351d8e1c3c275d1287d1e77015..f740d4fe43101c687c0929b4762e561772a17fc4 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -1121,10 +1121,6 @@ class BinaryPrinter extends Visitor {
   visitTypeParameterType(TypeParameterType node) {
     writeByte(Tag.TypeParameterType);
     writeUInt30(_typeParameterIndexer[node.parameter]);
-    List<TypeParameter> typeParameters =
-        _typeParameterIndexer.indexList[node.parameter];
-    writeUInt30(typeParameters[0].binaryOffset);
-    writeUInt30(typeParameters.indexOf(node.parameter));
     writeOptionalNode(node.promotedBound);
   }
 
@@ -1240,14 +1236,11 @@ class SwitchCaseIndexer {
 
 class TypeParameterIndexer {
   final Map<TypeParameter, int> index = <TypeParameter, int>{};
-  final Map<TypeParameter, List<TypeParameter>> indexList =
-      <TypeParameter, List<TypeParameter>>{};
   int stackHeight = 0;
 
   void enter(List<TypeParameter> typeParameters) {
     for (var parameter in typeParameters) {
       index[parameter] = stackHeight;
-      indexList[parameter] = typeParameters;
       ++stackHeight;
     }
   }