Add IsStackAllocated helper for variables.

src/data-flow.cc

Index: src/data-flow.cc
diff --git a/src/data-flow.cc b/src/data-flow.cc
index 1a0cf1a18765cf4843b14b21be4ef2225e53caa3..6b45da02b93040d7e64d616f86f285be7b8c7d00 100644
--- a/src/data-flow.cc
+++ b/src/data-flow.cc
@@ -433,11 +433,7 @@ void FlowGraphBuilder::VisitAssignment(Assignment* expr) {
   ASSERT(var == NULL || prop == NULL);
   if (var != NULL) {
     Visit(expr->value());
-    Slot* slot = var->slot();
-    if (slot != NULL &&
-        (slot->type() == Slot::LOCAL || slot->type() == Slot::PARAMETER)) {
-      definitions_.Add(expr);
-    }
+    if (var->IsStackAllocated()) definitions_.Add(expr);
 
   } else if (prop != NULL) {
     Visit(prop->obj());
@@ -499,12 +495,8 @@ void FlowGraphBuilder::VisitUnaryOperation(UnaryOperation* expr) {
 void FlowGraphBuilder::VisitCountOperation(CountOperation* expr) {
   Visit(expr->expression());
   Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
-  if (var != NULL) {
-    Slot* slot = var->slot();
-    if (slot != NULL &&
-        (slot->type() == Slot::LOCAL || slot->type() == Slot::PARAMETER)) {
-      definitions_.Add(expr);
-    }
+  if (var != NULL && var->IsStackAllocated()) {
+    definitions_.Add(expr);
   }
   graph_.AppendInstruction(expr);
 }