Update parser early return type in ESNEXT (#3742)

This patch updates the early return types in the parser to SyntaxError instead of ReferenceError
in ESNEXT

This patch also includes a lot of tests for LeftHandSideExpression validation when using the = operator

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

tests/jerry/es.next/regression-test-issue-2528.js

@@ -12,4 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-for (/a/ in a => { }, a => { }, a => { }) throw 1
+try {
+  eval('for (/a/ in a => { }, a => { }, a => { }) throw 1');
+  assert(false);
+} catch (e) {
+  assert(e instanceof SyntaxError);
+}
+