[parser] reject AssignmentElements with non-ASSIGN initializer ops

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 760035dc7e6b7851de2264803910e703b8b7725f..679c2761a33c58fa491fb3d76bd8cff3b745874a 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -2112,6 +2112,12 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN, int flags,
     function_state_->AddProperty();
   }
 
+  if (op != Token::ASSIGN && is_pattern_element) {
+    classifier->RecordAssignmentPatternError(
+        Scanner::Location(lhs_beg_pos, scanner()->location().end_pos),
+        MessageTemplate::kInvalidDestructuringTarget);
+  }
+
   this->CheckAssigningFunctionLiteralToProperty(expression, right);
 
   if (fni_ != NULL) {