RFR: JDK-8170483: Remove modules_src_jake workaround for JavaFX transition to new module-info syntax

[Erik Joelsson]

When the last jake->jdk9 push was done, a temporary workaround for 
dealing with Javafx was needed. Javafx has now been fully updated to 
only deliver the new format so the workaround should be removed.

Bug: https://bugs.openjdk.java.net/browse/JDK-8170483
Webrev: http://cr.openjdk.java.net/~erikj/8170483/webrev.01/

/Erik