Implement IsRegExp operation (#3321)

Algorithm is based on ECMA-262 v6, 22.1.3.1.1

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

tests/jerry/es2015/regexp-construct.js

@@ -0,0 +1,30 @@
+// 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 r = RegExp ("a","gim");
+var r2 = RegExp (r,"gim");
+
+assert(r2.source === 'a');
+assert(r2.global === true);
+assert(r2.ignoreCase === true);
+assert(r2.multiline === true);
+
+var obj = { get source() { throw 5 }, [Symbol.match] : true }
+
+try {
+  new RegExp (obj);
+  assert(false)
+} catch (e) {
+  assert(e === 5);
+}