dart2js: Remove rethrow from the CPS and Tree IRs.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.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 tree_ir_builder;
 
 import '../common.dart';
 import '../constants/values.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import '../elements/elements.dart';
@@ skipping 392 matching lines @@
   /************************** TAIL EXPRESSIONS  **************************/
   //
   // Visit methods for tail expressions must return a statement directly
   // (not a function like interior and call expressions).
 
   Statement visitThrow(cps_ir.Throw node) {
     Expression value = getVariableUse(node.value);
     return new Throw(value);
   }
 
-  Statement visitRethrow(cps_ir.Rethrow node) {
-    return new Rethrow();
-  }
-
   Statement visitUnreachable(cps_ir.Unreachable node) {
     return new Unreachable();
   }
 
   Statement visitInvokeContinuation(cps_ir.InvokeContinuation node) {
     // Invocations of the return continuation are translated to returns.
     // Other continuation invocations are replaced with assignments of the
     // arguments to formal parameter variables, followed by the body if
     // the continuation is singly reference or a break if it is multiply
     // referenced.
@@ skipping 310 matching lines @@
   @override
   Expression visitAwait(cps_ir.Await node) {
     return new Await(getVariableUse(node.input));
   }
 
   @override
   visitRefinement(cps_ir.Refinement node) {
     return (Statement next) => next; // Compile to nothing.
   }
 
-  @override
-  Expression visitBoundsCheck(cps_ir.BoundsCheck node) {
-    throw 'Unexpected BoundsCheck node in tree builder';
-  }
-
   /********** UNUSED VISIT METHODS *************/
 
   unexpectedNode(cps_ir.Node node) {
     internalError(CURRENT_ELEMENT_SPANNABLE, 'Unexpected IR node: $node');
   }
 
   visitFunctionDefinition(cps_ir.FunctionDefinition node) {
     unexpectedNode(node);
   }
   visitParameter(cps_ir.Parameter node) => unexpectedNode(node);
   visitContinuation(cps_ir.Continuation node) => unexpectedNode(node);
   visitMutableVariable(cps_ir.MutableVariable node) => unexpectedNode(node);
+  visitRethrow(cps_ir.Rethrow node) => unexpectedNode(node);
+  visitBoundsCheck(cps_ir.BoundsCheck node) => unexpectedNode(node);
 }