[TIMOB-13358] Code Analyzer: Native methods that modify their objects don't respect ambiguous blocks

If a native method is called that modifies the base object and is in an ambiguous block, it needs to convert the object to unknown. For example:

var x = ['1', '2', '3'];
if (Date.now()) {
	delete x[2];
} else {
	x[2] = x[2].length + 1;
}
console.log(x.join());

both branches of the if are evaluated, but the first branch is evaluated first and deletes x[2] before the second branch is evaluated, resulting in a "undefined value has no property "length"" exception. Instead, the array needs to be converted to unknown.