dart2js: Remove rethrow from the CPS and Tree IRs.

pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
index 8c6549b301113672957abc9087a81ab2cd924ed8..19eeb057d19d576d2d1204fc8dfd6225df89d3ff 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_nodes.dart
@@ -607,21 +607,6 @@ class Throw extends Statement {
   accept1(StatementVisitor1 visitor, arg) => visitor.visitThrow(this, arg);
 }
 
-/// A rethrow of an exception.
-///
-/// Rethrow can only occur nested inside a catch block.  It implicitly throws
-/// the block's caught exception value without changing the caught stack
-/// trace.  It does not have a successor statement.
-class Rethrow extends Statement {
-  Statement get next => null;
-  void set next(Statement s) => throw 'UNREACHABLE';
-
-  Rethrow();
-
-  accept(StatementVisitor visitor) => visitor.visitRethrow(this);
-  accept1(StatementVisitor1 visitor, arg) => visitor.visitRethrow(this, arg);
-}
-
 /**
  * A conditional branch based on the true value of an [Expression].
  */
@@ -1080,7 +1065,6 @@ abstract class StatementVisitor<S> {
   S visitLabeledStatement(LabeledStatement node);
   S visitReturn(Return node);
   S visitThrow(Throw node);
-  S visitRethrow(Rethrow node);
   S visitBreak(Break node);
   S visitContinue(Continue node);
   S visitIf(If node);
@@ -1099,7 +1083,6 @@ abstract class StatementVisitor1<S, A> {
   S visitLabeledStatement(LabeledStatement node, A arg);
   S visitReturn(Return node, A arg);
   S visitThrow(Throw node, A arg);
-  S visitRethrow(Rethrow node, A arg);
   S visitBreak(Break node, A arg);
   S visitContinue(Continue node, A arg);
   S visitIf(If node, A arg);
@@ -1198,8 +1181,6 @@ abstract class RecursiveVisitor implements StatementVisitor, ExpressionVisitor {
     visitExpression(node.value);
   }
 
-  visitRethrow(Rethrow node) {}
-
   visitBreak(Break node) {}
 
   visitContinue(Continue node) {}
@@ -1439,8 +1420,6 @@ class RecursiveTransformer extends Transformer {
     return node;
   }
 
-  visitRethrow(Rethrow node) => node;
-
   visitBreak(Break node) => node;
 
   visitContinue(Continue node) => node;