Fix named function expression creation. (#2634)

Create a local lexical environment with the name of the function. While
this is not too memory efficient, some corner cases requires its existence.

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

tests/jerry/function-expr-named.js

@@ -0,0 +1,51 @@
+// 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.
+
+var expr = "Dummy value";
+
+var f = function expr() {
+  assert(expr === f);
+  expr = 6;
+  assert(expr === f);
+  assert(!(delete expr));
+  assert(expr === f);
+}
+
+f();
+
+f = function expr() {
+  assert(expr === undefined);
+  var expr = 6;
+  assert(expr === 6);
+}
+
+f();
+
+var f = function expr() {
+  assert(expr === f);
+  eval("var expr = 8");
+  assert(expr === 8);
+}
+
+f();
+
+var f = function expr(i) {
+  assert(expr === f);
+
+  if (i > 0) {
+    expr(i - 1);
+  }
+}
+
+f(10);