On my symbian/gcce build I can't build webkit, so the default config sets it to not compile webkit. I indeed see the configure shell script print webkit should not be compiled.
To my surprise it actually is compiled and linked (which fails on the symbian/gcce setup, as expected).

I'd expect that if configure decides not to compile webkit that it doesn't get compiled.

My guess why its being compiled is because the mkspecs/modules/qt_webkit_version.pri has a QT_CONFIG += webkit