[es7] implement exponentiation operator proposal

src/parsing/scanner.h

Index: src/parsing/scanner.h
diff --git a/src/parsing/scanner.h b/src/parsing/scanner.h
index 9f195e3657fae6e90a2417f52ba6e0497c80a504..0cde0c2c02b79dd172cdbd613d8717af8c01f745 100644
--- a/src/parsing/scanner.h
+++ b/src/parsing/scanner.h
@@ -450,6 +450,12 @@ class Scanner {
 
   bool FoundHtmlComment() const { return found_html_comment_; }
 
+#define DECLARE_ACCESSORS(name)                                \
+  inline bool allow_##name() const { return allow_##name##_; } \
+  inline void set_allow_##name(bool allow) { allow_##name##_ = allow; }
+  DECLARE_ACCESSORS(harmony_exponentiation_operator)
+#undef ACCESSOR
+
  private:
   // The current and look-ahead token.
   struct TokenDesc {
@@ -758,6 +764,8 @@ class Scanner {
 
   // Whether this scanner encountered an HTML comment.
   bool found_html_comment_;
+
+  bool allow_harmony_exponentiation_operator_;
 };
 
 }  // namespace internal