Disable tests for two snippets that accidentally passed

Author: marijnh

02_program_structure.txt

@@ -629,13 +629,17 @@ operator)))(((*= operator)))(((state)))Especially when
 looping, a program often needs to “update” a variable with a value based
 on that variable's previous value.
 
+// test: no
+
 [source,javascript]
 ----
 counter = counter + 1;
 ----
 
 JavaScript provides a shortcut for this:
 
+// test: no
+
 [source,javascript]
 ----
 counter += 1;