Support decimal create with leading zero (#4286)

JerryScript-DCO-1.0-Signed-off-by: bence gabor kis kisbg@inf.u-szeged.hu

tests/jerry/es.next/decimal-with-leading-zero.js

@@ -0,0 +1,47 @@
+// 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.
+
+// valid decimal with leading zero
+assert (01239 === 1239)
+assert (0999 === 999)
+assert (0000000000009 === 9)
+
+function invalid_strict_cases (string)
+{
+  "use strict"
+  try {
+    eval (string)
+    assert (false)
+  } catch (e) {
+    assert (true)
+  }
+}
+
+// invalid strict test-cases
+invalid_strict_cases ("09")
+invalid_strict_cases ("01239")
+
+// invalid to create bigint with decimal with leading zero
+function invalid_cases (string)
+{
+  try {
+    eval (string)
+    assert (false)
+  } catch (e) {
+    assert (true)
+  }
+}
+
+invalid_cases ("09n")
+invalid_cases ("01239n")