Raise SyntaxError on let [ starting an ExpressionStatement

test/mjsunit/invalid-source-element.js

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@@ skipping 11 matching lines @@
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 // A function expression with no parenthesis around it is not a valid
 // expression statement.
 assertThrows("eval('function() {}')");
+
+// An expression statements must not start with "let [".
+assertThrows("function() { with ({}) let [a] = [];}", SyntaxError);

[Dan Ehrenberg, 2017/02/16 09:16:52]

Could you add a "messages" test, similar to
test/message/let-lexical-name-in-array-prohibited.js? This will have a few
benefits:
- Tests the preparser as well as the parser
- Tests that the particular error message that you added is the one that is used

[vabr (Chromium), 2017/02/16 17:09:33]

Thanks for teaching me about the "messages" tests.
I did as you suggested, and I am removing this mjsunit change, because it is now
redundant.