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

pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart

Index: pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
index b5e1a578ed926a70ee12fba49bca79123ce5a7ad..80ad3f1ef791b959f9fea10eb7cf4dc2d9313ca1 100644
--- a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
@@ -213,10 +213,10 @@ class RuntimeTypeGenerator {
     // [Function] and needs checks for all typedefs that are used in is-checks.
     if (checkedClasses.contains(compiler.functionClass) ||
         checkedFunctionTypes.isNotEmpty) {
-      Element call = cls.lookupLocalMember(Compiler.CALL_OPERATOR_NAME);
+      Element call = cls.lookupLocalMember(Identifiers.call);
       if (call == null) {
         // If [cls] is a closure, it has a synthetic call operator method.
-        call = cls.lookupBackendMember(Compiler.CALL_OPERATOR_NAME);
+        call = cls.lookupBackendMember(Identifiers.call);
       }
       if (call != null && call.isFunction) {
         FunctionElement callFunction = call;