Fix bug with illegal spread as single arrow parameter

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 dc08f5c5803923dd9ee29bf92228af10d5f0efe3..9b1a2dcabda5748fa0d7da3fcee22de15f83b857 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -1592,8 +1592,11 @@ ParserBase<Traits>::ParsePrimaryExpression(ExpressionClassifier* classifier,
                                           MessageTemplate::kUnexpectedToken,
                                           Token::String(Token::ELLIPSIS));
         classifier->RecordNonSimpleParameter();
-        ExpressionT expr =
-            this->ParseAssignmentExpression(true, classifier, CHECK_OK);
+        ExpressionClassifier binding_classifier(this);
+        ExpressionT expr = this->ParseAssignmentExpression(
+            true, &binding_classifier, CHECK_OK);
+        classifier->Accumulate(&binding_classifier,
+                               ExpressionClassifier::AllProductions);

[nickie, 2016/06/22 09:35:55]

This is now identical to the code handling spreads after the comma, in
ParseExpression.

         if (!this->IsIdentifier(expr) && !IsValidPattern(expr)) {
           classifier->RecordArrowFormalParametersError(
               Scanner::Location(ellipsis_pos, scanner()->location().end_pos),