[9] Review request: 8169683: Incremental build of WebKit native library is broken

[Kevin Rushforth]

Dave,

Please review:
https://bugs.openjdk.java.net/browse/JDK-8169683

The patch is in JBS. It is a simple one-line change to restore the 
behavior for native WebKit builds prior to the recent build changes to 
build with a Jigsaw-aware javac.

-- Kevin