Implement the function.sent proposal.

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index 73bf3e80e8944a80d4b9ce2a2c9d39f99216aa53..c0b892e954fd0d7a48b686c8450c5cdbe55574f8 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -2586,6 +2586,23 @@ ParserBase<Traits>::ParseMemberExpression(ExpressionClassifier* classifier,
 
     Consume(Token::FUNCTION);
     int function_token_position = position();
+
+    if (FLAG_harmony_function_sent && Check(Token::PERIOD)) {
+      // function.sent
+
+      int pos = position();
+      ExpectContextualKeyword(CStrVector("sent"), CHECK_OK);
+
+      if (!is_generator()) {

[rossberg, 2016/01/22 14:13:06]

This may not be good enough. Like other magic constants, function.sent is
probably intended to be accessible in nested arrow functions, e.g.

  function *g() { yield; return (() => function.sent))() }

I think it's fine to leave it like that for now, until there is a more detailed
spec, but at least add a TODO.

[neis, 2016/01/27 16:49:40]

Done.

+        ReportMessageAt(scanner()->location(),
+                        MessageTemplate::kUnexpectedFunctionSent);
+        *ok = false;
+        return this->EmptyExpression();
+      }
+
+      return this->FunctionSentExpression(scope_, factory(), pos);
+    }
+
     bool is_generator = Check(Token::MUL);
     IdentifierT name = this->EmptyIdentifier();
     bool is_strict_reserved_name = false;