Add new runtime tests

tests/jerry/arithmetics.js

@@ -12,9 +12,20 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-var a = 1;
-var b = 2;
+assert((1 + 2) == 3);
+assert((2 + 1) == 3);
+assert((2 + 1) != 4);
 
-assert(a+b == 3);
-assert(b+a == 3);
-assert(b+a != 4);
+assert((7 + 7) == 14);
+assert((7 - 7) == 0);
+assert((7 * 7) == 49);
+assert((7 / 7) == 1);
+assert((7 + 7) == 14);
+assert((7 % 7) == 0);
+
+var number = 81;
+assert((number + 9) == 90);
+assert((number - 9) == 72);
+assert((number * 10) == 810);
+assert((number / 9) == 9);
+assert((number % 79) == 2);