Remove unnecessary AST node for ++ and -- operations.

src/rewriter.cc

Index: src/rewriter.cc
===================================================================
--- src/rewriter.cc	(revision 7507)
+++ src/rewriter.cc	(working copy)
@@ -432,11 +432,6 @@
 }
 
 
-void AstOptimizer::VisitIncrementOperation(IncrementOperation* node) {
-  UNREACHABLE();
-}
-
-
 void AstOptimizer::VisitCountOperation(CountOperation* node) {
   // Count operations assume that they work on Smis.
   node->expression()->set_no_negative_zero(node->is_prefix() ?
@@ -943,11 +938,6 @@
 }
 
 
-void Processor::VisitIncrementOperation(IncrementOperation* node) {
-  UNREACHABLE();
-}
-
-
 void Processor::VisitCountOperation(CountOperation* node) {
   USE(node);
   UNREACHABLE();