Intellisense isn't a feature of the language, its a feature of the IDE you are using.
How exactly is intellisense a feature of a language?
While you're right that intelligent autocompletion is not a feature of a programming language, clearly it's much easier to create one for some languages than for others. It's not a coincidence that there's still aren't any really usable intelligent autocompleting editors for JavaScript but there is a number of very high quality ones for C# and Java.