I checked back to the two last times I compiled qt-5.x and no files named *QWebElement* were installed.
Looking at: Qt WebEngine:
Embedded build ......................... no
Pepper Plugins ......................... yes
Printing and PDF ....................... yes
Proprietary Codecs ..................... no
Spellchecker ........................... yes
Native Spellchecker .................... no
WebRTC ................................. yes
Use System Ninja ....................... no
Geolocation ............................ yes
Use v8 snapshot ........................ yes
Use ALSA ............................... yes
Use PulseAudio ......................... yes
Optional system libraries used:
re2 .................................. no
icu .................................. no
libwebp, libwebpmux and libwebpdemux . yes
opus ................................. yes
ffmpeg ............................... no
libvpx ............................... no
snappy ............................... no
libsrtp .............................. no
glib ................................. yes
zlib ................................. yes
minizip .............................. no
libevent ............................. no
jsoncpp .............................. no
protobuf ............................. no
libxml2 and libxslt .................. no
lcms2 ................................ yes
png .................................. yes
JPEG ................................. yes
harfbuzz ............................. yes
freetype ............................. yes
..perhaps it is due to one of the missing deps, but, if so, which one?