The backport was applied incorrectly, it misses the import statement in src/windows/classes/sun/awt/windows/WToolkit.java:
 import sun.awt.DisplayChangedListener;

Which causes Windows builds to fail:

Compiling 9228 files for BUILD_JDK
c:\Work\jdk8u-jdk8u-dev\jdk\src\windows\classes\sun\awt\windows\WToolkit.java:843: error: cannot find symbol
            if (lge instanceof DisplayChangedListener) {
                               ^
  symbol: class DisplayChangedListener
  location: class WToolkit
c:\Work\jdk8u-jdk8u-dev\jdk\src\windows\classes\sun\awt\windows\WToolkit.java:844: error: cannot find symbol
                ((DisplayChangedListener) lge).displayChanged();
                  ^
  symbol: class DisplayChangedListener
  location: class WToolkit