Remove cancel and make crash exit with code 253.

sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.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 js_backend;
 
 class NativeEmitter {
 
   CodeEmitterTask emitter;
   CodeBuffer nativeBuffer;
@@ skipping 425 matching lines @@
       arguments = argumentsBuffer.sublist(0,
           indexOfLastOptionalArgumentInParameters + 1);
     }
     statements.add(new jsAst.Return(receiver[target](arguments)));
 
     return statements;
   }
 
   bool isSupertypeOfNativeClass(Element element) {
     if (element.isTypeVariable()) {
-      compiler.cancel("Is check for type variable", element: element);
+      compiler.internalError(element, "Is check for type variable.");
       return false;
     }
     if (element.computeType(compiler).unalias(compiler) is FunctionType) {
       // The element type is a function type either directly or through
       // typedef(s).
       return false;
     }
 
     if (!element.isClass()) {
-      compiler.cancel("Is check does not handle element", element: element);
+      compiler.internalError(element, "Is check does not handle element.");
       return false;
     }
 
     if (backend.classesMixedIntoInterceptedClasses.contains(element)) {
       return true;
     }
 
     return subtypes[element] != null;
   }
 
@@ skipping 43 matching lines @@
       if (emitter.compiler.enableMinification) targetBuffer.add(';');
       targetBuffer.add(jsAst.prettyPrint(
           new jsAst.ExpressionStatement(init), compiler));
       targetBuffer.add('\n');
     }
 
     targetBuffer.add(nativeBuffer);
     targetBuffer.add('\n');
   }
 }