[destructuring] Implement spread binding patterns.

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 60f0068d37aebe855c31c352469af4d9ca058bf5..74c0194f8d9ba5a741fed7fe8151aa0f979551b7 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -2204,16 +2204,26 @@ class Spread final : public Expression {
 
   Expression* expression() const { return expression_; }
 
+  int literal_index() const {
+    DCHECK(literal_index_ >= 0);
+    return literal_index_;
+  }
+
   static int num_ids() { return parent_num_ids(); }
 
  protected:
-  Spread(Zone* zone, Expression* expression, int pos)
-      : Expression(zone, pos), expression_(expression) {}
+  Spread(Zone* zone, Expression* expression, int literal_index, int pos)
+      : Expression(zone, pos),
+        literal_index_(literal_index),
+        expression_(expression) {}
   static int parent_num_ids() { return Expression::num_ids(); }
 
  private:
   int local_id(int n) const { return base_id() + parent_num_ids() + n; }
 
+  // Literal index is only used when Spread is renterpreted as a pattern.

[rossberg, 2015/05/20 12:57:35]

Nit: typo

[Dmitry Lomov (no reviews), 2015/05/20 14:22:02]

Undid this change.

+  int literal_index_;
+
   Expression* expression_;
 };
 
@@ -3424,8 +3434,8 @@ class AstNodeFactory final BASE_EMBEDDED {
     return new (zone_) CompareOperation(zone_, op, left, right, pos);
   }
 
-  Spread* NewSpread(Expression* expression, int pos) {
-    return new (zone_) Spread(zone_, expression, pos);
+  Spread* NewSpread(Expression* expression, int literal_index, int pos) {
+    return new (zone_) Spread(zone_, expression, literal_index, pos);
   }
 
   Conditional* NewConditional(Expression* condition,