Bug 20683 – errors in static assert do not halt compilation immediately

``` static assert(somethingBogus); static assert(false); ``` Normally, when a static assert's expression evaluates to false, compilation is halted immediately. However, this doesn't happen when there is an error in the expression. In this situation, I would expect the appropriate error for the statement to be issued and for compilation to halt before the second static assert is evaluated.

Having an error in the static assert expression does not mean that the expression is false (or true). It means that a mistake has been made that needs to be reported. The compiler is right to report the error and continue compilation.