[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 f3d181eb68a1508333b49d90fba3f46025e08b4c..e889eaad32b6d7ccdb20ee615e2cf1a206b2c12f 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -1164,10 +1164,6 @@ 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);
   }
 
@@ -1283,14 +1279,11 @@ 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;
     }
   }