cd && cd Downloads
wget https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/plank/0.11.89-1/plank_0.11.89.orig.tar.xz
tar xf plank_0.11.89.orig.tar.xz
cd plank-0.11.89
./configure
make
sudo make install
sudo apt install --reinstall plank libplank*
Additionally to enable zoom in Plank:
Two files need to be edited before you can get the zoom effect, copy/paste.
sudo nano /usr/local/share/plank/themes/Default/dock.theme
Add the following in the end of the file;
ZoomEnabled=true
ZoomPercent=150
Save: [ctrl]+[o] and Exit: [ctrl]+[x]
The last file to edit is the schema file of Plank.
sudo nano /usr/share/glib-2.0/schemas/net.launchpad.plank.gschema.xml
Look for (near the end of the file).
false
Change false to true
Save: [ctrl]+[o] and Exit: [ctrl]+[x]
Last thing.
killall plank&& plank&
plank --preferences
Now enable Zoom effect in preferences.