dart2js: Rename old emitter to full emitter and make it its own library.

tests/compiler/dart2js/mirrors_used_test.dart

Index: tests/compiler/dart2js/mirrors_used_test.dart
diff --git a/tests/compiler/dart2js/mirrors_used_test.dart b/tests/compiler/dart2js/mirrors_used_test.dart
index 53101cd5c5b2945870c38ce830db183f579b7bdc..e79df96799cbb1bbd14624d04b508131717014a7 100644
--- a/tests/compiler/dart2js/mirrors_used_test.dart
+++ b/tests/compiler/dart2js/mirrors_used_test.dart
@@ -26,6 +26,9 @@ import 'package:compiler/src/elements/elements.dart' show
 import 'package:compiler/src/js_backend/js_backend.dart' show
     JavaScriptBackend;
 
+import 'package:compiler/src/js_emitter/full_emitter/emitter.dart'
+    as full show Emitter;
+
 void expectOnlyVerboseInfo(Uri uri, int begin, int end, String message, kind) {
   if (kind.name == 'verbose info') {
     print(message);
@@ -91,7 +94,7 @@ void main() {
 
     // Mirrors only work in the full emitter. We can thus be certain that the
     // emitter is the full emitter.
-    OldEmitter fullEmitter = backend.emitter.emitter;
+    full.Emitter fullEmitter = backend.emitter.emitter;
     Set recordedNames = new Set()
         ..addAll(fullEmitter.recordedMangledNames)
         ..addAll(fullEmitter.mangledFieldNames.keys)