Move common identifiers, names and selectors to a separate library.

tests/compiler/dart2js/cpa_inference_test.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.
 
 import 'dart:async';
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import 'package:compiler/src/types/types.dart';
 import 'package:compiler/src/inferrer/concrete_types_inferrer.dart';
 import 'package:compiler/src/universe/universe.dart' show Selector;
@@ skipping 1630 matching lines @@
     var world = result.compiler.world;
 
     ClassElement a = findElement(result.compiler, 'A');
     ClassElement b = findElement(result.compiler, 'B');
     ClassElement c = findElement(result.compiler, 'C');
     ClassElement xy = findElement(result.compiler, 'XY');
     ClassElement x = findElement(result.compiler, 'X');
     ClassElement y = findElement(result.compiler, 'Y');
     ClassElement z = findElement(result.compiler, 'Z');
 
-    Selector foo = new Selector.call("foo", null, 0);
+    Selector foo = new Selector.call(const PublicName("foo"), 0);
 
     result.checkSelectorHasType(
         foo,
         null,
         new TypeMask.unionOf([a, b, c]
             .map((cls) => new TypeMask.nonNullExact(cls, world)),
             result.compiler.world));
     result.checkSelectorHasType(
         foo,
         new TypeMask.subclass(x, world),
         new TypeMask.nonNullExact(b, world));
     result.checkSelectorHasType(
         foo,
         new TypeMask.subclass(y, world),
         new TypeMask.nonNullExact(c, world));
     result.checkSelectorHasType(
         foo,
         new TypeMask.subclass(z, world),
         new TypeMask.nonNullExact(a, world));
     result.checkSelectorHasType(
         foo,
         new TypeMask.subclass(xy, world),
         new TypeMask.unionOf([b, c].map((cls) =>
             new TypeMask.nonNullExact(cls, world)), world));
 
-    result.checkSelectorHasType(new Selector.call("bar", null, 0), null, null);
+    result.checkSelectorHasType(
+        new Selector.call(const PublicName("bar"), 0), null, null);
   });
 }
 
 testEqualsNullSelector() {
   final String source = r"""
       main() {
         1 == null;
       }
       """;
   return analyze(source).then((result) {
@@ skipping 457 matching lines @@
     testClosures10,
     testClosures11,
     testClosures12,
     testRefinement,
     testDefaultArguments,
     testSuperConstructorCall,
     testSuperConstructorCall2,
     testSuperConstructorCall3,
   ], (f) => f()));
 }