Support assignment expressions in the pre-scanner. (#3382)

Fixes #3355.

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

tests/jerry/es2015/arrow-assignment.js

@@ -0,0 +1,46 @@
+/* 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 y = 0
+var prot = Object.getPrototypeOf(/ /)
+
+prot.setY = function (v) { y = v }
+
+assert(y === 0)
+// Since arrow function is an assignment expression, this affects certain constructs
+var f = x => {}
+/ /.setY(5)
+assert(y === 5)
+
+var s
+// This is not a function call
+assert(eval("s = x => { return 1 }\n(3)") === 3)
+assert(typeof s === "function")
+
+// This is a function call
+assert(eval("s = function () { return 1 }\n(3)") === 1)
+assert(s === 1)
+
+var f = 5 ? x => 1 : x => 2
+assert(f() === 1)
+
+var f = [x => 2][0]
+assert(f() === 2)
+
+var f = 123; f += x => y
+assert(typeof f === "string")
+
+// Comma operator
+assert(eval("x => {}, 5") === 5)