dart2js: Remove rethrow from the CPS and Tree IRs.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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.
 
 library code_generator;
 
 import 'glue.dart';
 
 import '../../closure.dart' show
     ClosureClassElement;
@@ skipping 771 matching lines @@
             .withSourceInformation(node.sourceInformation));
     }
   }
 
   @override
   void visitThrow(tree_ir.Throw node) {
     accumulator.add(new js.Throw(visitExpression(node.value)));
   }
 
   @override
-  void visitRethrow(tree_ir.Rethrow node) {
-    glue.reportInternalError('rethrow seen in JavaScript output');
-  }
-
-  @override
   void visitUnreachable(tree_ir.Unreachable node) {
     if (emitUnreachableAsReturn.last) {
       // Emit a return to assist local analysis in the VM.
       accumulator.add(new js.Return());
     }
   }
 
   @override
   void visitTry(tree_ir.Try node) {
     js.Block tryBlock = buildBodyBlock(node.tryBody);
@@ skipping 423 matching lines @@
   void registerDefaultParameterValues(ExecutableElement element) {
     if (element is! FunctionElement) return;
     FunctionElement function = element;
     if (function.isStatic) return; // Defaults are inlined at call sites.
     function.functionSignature.forEachOptionalParameter((param) {
       ConstantValue constant = glue.getDefaultParameterValue(param);
       registry.registerCompileTimeConstant(constant);
     });
   }
 }