dart2Js: bailout early when using the new emitter with mirrors.

pkg/compiler/lib/src/compiler.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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 1202 matching lines @@
   /// Use this callback method to store references to specific libraries.
   /// Note that [library] has not been scanned yet, nor has its imports/exports
   /// been resolved.
   void onLibraryCreated(LibraryElement library) {
     Uri uri = library.canonicalUri;
     if (uri == DART_CORE) {
       coreLibrary = library;
     } else if (uri == DART_NATIVE_TYPED_DATA) {
       typedDataLibrary = library;
     } else if (uri == DART_MIRRORS) {
+      if (const bool.fromEnvironment("dart2js.use.new.emitter")) {
+        internalError(library,

[floitsch, 2015/02/27 14:05:50]

This should not be an internal error, but a "reportError" or similar. The string
should be in "warnings.dart".

I would put this close to the already existing warning in line 1325.

[zarah, 2015/03/02 10:42:36]

Done.

+            "dart:mirrors library is not supported when using the new emitter "
+            "(DART_VM_OPTIONS='-Ddart2js.use.new.emitter=true')");
+      }
+
       mirrorsLibrary = library;
     }
     backend.onLibraryCreated(library);
   }
 
   /// This method is called immediately after the [library] and its parts have
   /// been scanned.
   ///
   /// Use this callback method to store references to specific member declared
   /// in certain libraries. Note that [library] has not been patched yet, nor
@@ skipping 1175 matching lines @@
     return futureClass.computeType(compiler).createInstantiation([elementType]);
   }
 
   @override
   InterfaceType streamType([DartType elementType = const DynamicType()]) {
     return streamClass.computeType(compiler).createInstantiation([elementType]);
   }
 }
 
 typedef void InternalErrorFunction(Spannable location, String message);