Fix 'continue' bytecode generation. Fix tests.

tests/jerry-test-suite/12/12.06/12.06.01/12.06.01-004.js

@@ -13,8 +13,9 @@
 // limitations under the License.
 
 var obj = new Object();
+obj.x = "defined";
 do
 {
-  obj.x = "defined";
+  delete obj.x;
 }
-while (delete obj.x);
+while (obj.x !== undefined);

tests/jerry-test-suite/12/12.06/12.06.01/12.06.01-005.js

@@ -15,5 +15,7 @@
 var x = 1 / 3;
 do
 {
+  x = 1;
 }
 while (x === 3 / 9);
+assert (x === 1);