[parser] Fix scopes in rewriting of for-of and destructuring assignments.

src/ast/scopes.cc

Index: src/ast/scopes.cc
diff --git a/src/ast/scopes.cc b/src/ast/scopes.cc
index c150336668545eb1a8bf78b3af3823f70bb476c1..fc86e60257d8c2308aec20dd728bb7916f0e9d3d 100644
--- a/src/ast/scopes.cc
+++ b/src/ast/scopes.cc
@@ -636,6 +636,24 @@ Variable* DeclarationScope::DeclareFunctionVar(const AstRawString* name) {
   return function_;
 }
 
+bool Scope::HasBeenRemoved() const {
+  if (!is_block_scope() || is_declaration_scope()) return false;  // Shortcut.

[Toon Verwaest, 2016/11/23 12:20:45]

if (is_declaration_scope()) return false;
DCHECK(is_block_scope());

[neis, 2016/11/23 15:52:38]

This DCHECK is failing, for instance in the following nonsense code:

for(let y in [5,6,7,8]) with({}) { let([, [x4]] = ([new (undefined)(-1)]), [] =
[11,12,13,14].map) ((function(){throw StopIteration;})()); } 

where it's a with scope.

+
+  Scope* parent = outer_scope();
+  if (parent == nullptr) {
+    DCHECK(is_script_scope());
+    return false;
+  }
+
+  Scope* sibling = parent->inner_scope();
+  for (; sibling != nullptr; sibling = sibling->sibling()) {
+    if (sibling == this) return false;
+  }
+
+  DCHECK_NULL(inner_scope_);
+  return true;
+}
+
 Scope* Scope::FinalizeBlockScope() {
   DCHECK(is_block_scope());