Use LibraryIndex in CoreTypes instead of extending it.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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.
 
 library fasta.body_builder;
 
 import '../fasta_codes.dart'
     show FastaMessage, codeExpectedButGot, codeExpectedFunctionBody;
 
 import '../parser/parser.dart' show FormalParameterType, MemberKind, optional;
@@ skipping 594 matching lines @@
       push(receiver);
     } else {
       push(finishSend(receiver, arguments, beginToken.charOffset));
     }
   }
 
   @override
   finishSend(Object receiver, Arguments arguments, int charOffset) {
     bool isIdentical(Object receiver) {
       return receiver is StaticAccessor &&
-          receiver.readTarget ==
-              coreTypes.tryGetTopLevelMember("dart:core", null, "identical");
+          receiver.readTarget == coreTypes.identicalProcedure;
     }
 
     if (receiver is FastaAccessor) {
       if (constantExpressionRequired &&
           !isIdentical(receiver) &&
           !receiver.isInitializer) {
         addCompileTimeError(charOffset, "Not a constant expression.");
       }
       return receiver.doInvocation(charOffset, arguments);
     } else {
@@ skipping 150 matching lines @@
     } else if (isSetter) {
       message = "Setter not found: '$errorName'.";
     } else {
       message = "Method not found: '$errorName'.";
     }
     if (constantExpressionRequired) {
       return buildCompileTimeError(message, charOffset);
     }
     warning(message, charOffset);
     Constructor constructor =
-        coreTypes.getClass("dart:core", "NoSuchMethodError").constructors.first;
+        coreTypes.noSuchMethodErrorClass.constructors.first;
     return new Throw(new ConstructorInvocation(
         constructor,
         astFactory.arguments(<Expression>[
           astFactory.nullLiteral(null),
           new SymbolLiteral(name),
           new ListLiteral(arguments.positional),
           new MapLiteral(arguments.named.map((arg) {
             return new MapEntry(new SymbolLiteral(arg.name), arg.value);
           }).toList()),
           astFactory.nullLiteral(null)
@@ skipping 2369 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }