Reverted some code which got accidentally committed as part of another commit.

TBR=vitalyr@chromium.org
Review URL: http://codereview.chromium.org/6994011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7842 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen.cc

@@ -4637,10 +4637,6 @@ void HGraphBuilder::VisitSub(UnaryOperation* expr) {
   CHECK_ALIVE(VisitForValue(expr->expression()));
   HValue* value = Pop();
   HInstruction* instr = new(zone()) HMul(value, graph_->GetConstantMinus1());
-
-  Representation rep = ToRepresentation(oracle()->UnaryType(expr));
-  AssumeRepresentation(instr, rep);
-
   ast_context()->ReturnInstruction(instr, expr->id());
 }