Looks like STLPort is not used in Mozilla...
However I took a look at nsViewManager.cpp(1695) and low and behold, I find this just before it...
// This gets around an internal compiler error C1001
// (compiler file 'E:\8799\vc98\p2\src\P2\main.c', line 494)
#ifdef WINCE
#pragma optimize( "", off )
#endif
AHA! Say I, but I'm not compiling for WinCE...
Perhaps I'll just comment out the #ifdef just to see what happens...