Initial implementation of class fields (#4191)

Missing features:
 - this binding in static fields are not supported
 - static field evaluation order is wrong
 - function names are not supported

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

tests/jerry/es.next/class-with.js

@@ -0,0 +1,31 @@
+/* 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 called = false
+var obj = { f() { assert(this === obj); called = true } }
+
+function f() {
+  assert(false)
+}
+
+with (obj) {
+  new class {
+    constructor() {
+      f()
+    }
+  }
+}
+
+assert(called)