Add tests for early errors in SwithStatement

test/language/statements/switch/early-lex-dup.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-switch-statement-static-semantics-early-errors
+es6id: 13.12.1
+description: Syntax error from duplicate lexical variables
+info: >
+  It is a Syntax Error if the LexicallyDeclaredNames of CaseBlock contains any
+  duplicate entries.
+negative: SyntaxError
+features: [let, const]
+---*/
+
+switch (0) {
+  case 1:
+    let test262id;
+    break;
+  default:
+    const test262id = null;
+}

test/language/statements/switch/early-lex-var-collision.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-switch-statement-static-semantics-early-errors
+es6id: 13.12.1
+description: >
+  Syntax error from collisions between lexical variables and var-declarared
+  variables
+info: >
+  It is a Syntax Error if any element of the LexicallyDeclaredNames of
+  CaseClauses also occurs in the VarDeclaredNames of CaseClauses.
+negative: SyntaxError
+features: [let]
+---*/
+
+switch (0) {
+  case 1:
+    var test262id;
+    break;
+  default:
+    let test262id;
+}