isExpressions -> isValuesSeq

[Shriramana Sharma via Digitalmars-d]

Mike Parker wrote:

> All values, 3 and false included, *are* expressions. They are
> expressions with one operand and no operator, but they are still
> expressions.
> 
> https://en.wikipedia.org/wiki/Value_(computer_science)

That's true, but the fact remains that the AliasSeq stores only the 
resultant value of the expression and not the expression itself (which may 
be valid or not).

-- 
Shriramana Sharma, Penguin #395953