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

pkg/compiler/lib/src/closure.dart

Index: pkg/compiler/lib/src/closure.dart
diff --git a/pkg/compiler/lib/src/closure.dart b/pkg/compiler/lib/src/closure.dart
index 0bf149d06d98c54f9bcaed0a072b7e2a62797300..d95c3f7746aab3754d8da039d2f055864e356f10 100644
--- a/pkg/compiler/lib/src/closure.dart
+++ b/pkg/compiler/lib/src/closure.dart
@@ -4,6 +4,8 @@
 
 library closureToClassMapper;
 
+import 'common/names.dart' show
+    Identifiers;
 import 'common/tasks.dart' show
     CompilerTask;
 import 'compiler.dart' show
@@ -992,10 +994,11 @@ class ClosureTranslator extends Visitor {
     ClosureClassElement globalizedElement = new ClosureClassElement(
         node, closureName, compiler, element);
     FunctionElement callElement =
-        new SynthesizedCallMethodElementX(Compiler.CALL_OPERATOR_NAME,
+        new SynthesizedCallMethodElementX(Identifiers.call,
                                           element,
                                           globalizedElement);
-    backend.maybeMarkClosureAsNeededForReflection(globalizedElement, callElement, element);
+    backend.maybeMarkClosureAsNeededForReflection(
+        globalizedElement, callElement, element);
     MemberElement enclosing = element.memberContext;
     enclosing.nestedClosures.add(callElement);
     globalizedElement.addMember(callElement, compiler);