[es6] implement destructuring assignment

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 7878d776bea72184afaed8c2be83036b97bb2b2c..6f5c0d44eb289933ce885e72c9a70814f0e4be38 100644
--- a/src/compiler/ast-loop-assignment-analyzer.cc
+++ b/src/compiler/ast-loop-assignment-analyzer.cc
@@ -288,6 +288,12 @@ void ALAA::VisitCountOperation(CountOperation* e) {
 }
 
 
+void ALAA::VisitRewritableAssignmentExpression(
+    RewritableAssignmentExpression* expr) {
+  Visit(expr->expression());
+}
+
+
 void ALAA::AnalyzeAssignment(Variable* var) {
   if (!loop_stack_.empty() && var->IsStackAllocated()) {
     loop_stack_.back()->Add(GetVariableIndex(info()->scope(), var));