[destructuring] Support computed property names in patterns.

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index b08888834eb9ba4a42c557f8cd2d3dfa849c9520..116a8eac9b891721e208bea92d9f3b7e4ad30528 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -2560,8 +2560,10 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParsePropertyName(
       if (allow_harmony_computed_property_names_) {
         *is_computed_name = true;
         Consume(Token::LBRACK);
-        ExpressionT expression =
-            ParseAssignmentExpression(true, classifier, CHECK_OK);
+        ExpressionClassifier computed_name_classifier;
+        ExpressionT expression = ParseAssignmentExpression(
+            true, &computed_name_classifier, CHECK_OK);
+        classifier->AccumulateReclassifyingAsPattern(computed_name_classifier);
         Expect(Token::RBRACK, CHECK_OK);
         return expression;
       }