Hi there Well I did reinstall my whole system but without luck. Emerging gnome-light showed the very same error when compiling spidermonkey.
Then I thought I will install awesome, because it does not need spidermonkey. But the same problem here when compiling awesome. `Illegal statement' in the build.log. Next I thought about installing xmonad. And this time it worked. So I will use xmonad for the future. Thanks for your help Nilesh and Walt! -- Greetings Elias