Issue 9879 - Built-in sizeof should return ErrorExp if error occurs in aggregate type semantics

http://d.puremagic.com/issues/show_bug.cgi?id=9879

This is an additional fix for [bug 4269](http://d.puremagic.com/issues/show_bug.cgi?id=4269). With this code, `__traits` should return `false`, but doesn't.

```d
static if(__traits(compiles,A.sizeof)) pragma(msg, "A.sizeof compiles!");
class A { void foo(B b); }
```