Nesting index multiplication assignment fixed

This affects all arithmetic types applied to inner-nested compounds.

scripts/small.toy

@@ -1,9 +1,6 @@
 
+var a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
 
-var d = ["foo" : ["bar" : ["bazz": ["fizz" : 5]]]];
+a[1][1] *= 10;
 
-print d;
-
-d["foo"]["bar"]["bazz"]["fizz"] = 66;
-
-print d;
+print a;