Implement iterator finalization in array destructuring.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index f838e3a518534aa345151d404d7d4d866b5550c1..dfe6ad8ed62e4bd3c6ea272519371641c4435dd1 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -466,6 +466,9 @@ class ParserTraits {
                             MessageTemplate::Template message,
                             const AstRawString* arg, int pos);
 
+  void FinalizeIteratorUse(Variable* completion, Expression* condition,
+      Variable* iter, Block* iterator_use, Block* result);
+
   Statement* FinalizeForOfStatement(ForOfStatement* loop, int pos);
 
   // Reporting errors.
@@ -706,6 +709,9 @@ class Parser : public ParserBase<ParserTraits> {
  private:
   friend class ParserTraits;
 
+  // Runtime encoding of different completion modes.
+  enum CompletionKind { NORMAL, THROW, ABRUPT };
+
   // Limit the allowed number of local variables in a function. The hard limit
   // is that offsets computed by FullCodeGenerator::StackOperand and similar
   // functions are ints, and they should not overflow. In addition, accessing