Wrong syntax accepted

Although it's invalid, the compiler does not complain about the following syntax:
```
DIM x, y AS LONG
```
One would assume that both `x` and `y` are defined as LONG, but this is not the case as `x` is defined as INT (because it is not followed by the AS keyword).

The correct syntax is
```
DIM x AS LONG, y AS LONG
```
The compiler should display an error in the first case.