[turbofan] Fix loop assignment analysis on ForInStatements.

src/compiler/ast-loop-assignment-analyzer.cc

Index: src/compiler/ast-loop-assignment-analyzer.cc
diff --git a/src/compiler/ast-loop-assignment-analyzer.cc b/src/compiler/ast-loop-assignment-analyzer.cc
index b1b666a728a276ab1fbe37d62fdcfc59b333a15a..82eaeb28a46840d5087c1b0baf1ea754282641bb 100644
--- a/src/compiler/ast-loop-assignment-analyzer.cc
+++ b/src/compiler/ast-loop-assignment-analyzer.cc
@@ -252,10 +252,12 @@ void ALAA::VisitForStatement(ForStatement* loop) {
 
 
 void ALAA::VisitForInStatement(ForInStatement* loop) {
+  Expression* l = loop->each();
   Enter(loop);
-  Visit(loop->each());
+  Visit(l);
   Visit(loop->subject());
   Visit(loop->body());
+  if (l->IsVariableProxy()) AnalyzeAssignment(l->AsVariableProxy()->var());
   Exit(loop);
 }