Refactor String.prototype.replace (#3284)

This change brings the replace operation up to date with ES6 by
implementing support for the @@replace well-known symbol, while
also improving performance and memory usage.

Also fixes #3070.

JerryScript-DCO-1.0-Signed-off-by: Dániel Bátyai dbatyai@inf.u-szeged.hu

tests/jerry/es5.1/string-prototype-replace.js

@@ -0,0 +1,18 @@
+// 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.
+
+// Changing exec should not affect replace.
+Object.getPrototypeOf(/x/).exec = function () { return 1234; }
+assert (/y/.exec("y") === 1234);
+assert ("y".replace (/y/, "x") === "x");