Keywords must not contain escape sequences. (#3429)

The ES5.1 standard is unclear about this rule.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/keyword.js

@@ -0,0 +1,47 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+function check_syntax_error(code)
+{
+  try {
+    eval(code)
+    assert(false)
+  } catch (e) {
+    assert(e instanceof SyntaxError)
+  }
+}
+
+function check_strict_syntax_error(code)
+{
+  "use strict"
+
+  try {
+    eval(code)
+    assert(false)
+  } catch (e) {
+    assert(e instanceof SyntaxError)
+  }
+}
+
+check_syntax_error("d\\u006f {} while (false)")
+check_syntax_error("\\u0076\\u0061\\u0072 var = 5")
+check_syntax_error("wit\\u0068 ({}) {}")
+check_syntax_error("\\u0066alse")
+check_syntax_error("type\\006ff 3.14")
+check_syntax_error("try {} fin\\u0061lly {}")
+check_syntax_error("f\\u0075nction f() {}")
+check_syntax_error("a instanc\\u0065of b")
+
+check_strict_syntax_error("\\u006c\\u0065\\u0074 _let = 5");
+check_strict_syntax_error("\\u0070rotecte\\u0064");