Add lookahead restriction tests for "let [" in expression statement contexts

test/language/statements/while/let-block-with-newline.js

+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-while-statement
+description: >
+  ExpressionStatement doesn't have a lookahead restriction for `let {`.
+info: |
+  ExpressionStatement[Yield, Await] :
+    [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]
+    Expression[+In, ?Yield, ?Await] ;
+flags: [noStrict]
+---*/
+
+while (false) let // ASI
+{}

test/language/statements/while/let-identifier-with-newline.js

+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-while-statement
+description: >
+  ExpressionStatement doesn't have a lookahead restriction for `let <binding-identifier>`.
+info: |
+  ExpressionStatement[Yield, Await] :
+    [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]
+    Expression[+In, ?Yield, ?Await] ;
+flags: [noStrict]
+---*/
+
+while (false) let // ASI
+x = 1;

test/language/statements/with/let-array-with-newline.js

+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-with-statement
+description: >
+  ExpressionStatement has a lookahead restriction for `let [`.
+info: |
+  ExpressionStatement[Yield, Await] :
+    [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]
+    Expression[+In, ?Yield, ?Await] ;
+negative:
+  phase: early
+  type: SyntaxError
+flags: [noStrict]
+---*/
+
+// Wrapped in an if-statement to avoid reference errors at runtime.
+if (false) {
+    with ({}) let
+    [a] = 0;
+}

test/language/statements/with/let-block-with-newline.js

+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-with-statement
+description: >
+  ExpressionStatement doesn't have a lookahead restriction for `let {`.
+info: |
+  ExpressionStatement[Yield, Await] :
+    [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]
+    Expression[+In, ?Yield, ?Await] ;
+flags: [noStrict]
+---*/
+
+// Wrapped in an if-statement to avoid reference errors at runtime.
+if (false) {
+    with ({}) let // ASI
+    {}
+}

test/language/statements/with/let-identifier-with-newline.js

+// Copyright (C) 2017 André Bargull. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-with-statement
+description: >
+  ExpressionStatement doesn't have a lookahead restriction for `let <binding-identifier>`.
+info: |
+  ExpressionStatement[Yield, Await] :
+    [lookahead ∉ { {, function, async [no LineTerminator here] function, class, let [ }]
+    Expression[+In, ?Yield, ?Await] ;
+flags: [noStrict]
+---*/
+
+// Wrapped in an if-statement to avoid reference errors at runtime.
+if (false) {
+    with ({}) let // ASI
+    x = 1;
+}