Raise SyntaxError on let [ starting an ExpressionStatement

test/mjsunit/invalid-source-element.js

Index: test/mjsunit/invalid-source-element.js
diff --git a/test/mjsunit/invalid-source-element.js b/test/mjsunit/invalid-source-element.js
index fb012e2267cfbfdaca6c48ba73757a091bb40c71..92bd455004ab2d829164b81454f741b9be666b47 100644
--- a/test/mjsunit/invalid-source-element.js
+++ b/test/mjsunit/invalid-source-element.js
@@ -29,3 +29,6 @@
 // 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);