For thus who are interested, please find below the Oracle response on this issue:
WebView uses the default JavaFX graphics pipeline, which is different than the one used for Swing/AWT. Support for right to left languages and complex characters is only planned for JDK 8 (JavaFX 8), but an early access implementation should soon be available as part of the JDK 8 weekly builds at http://jdk8.java.net/downloads.html
Whatever support for Arabic existing in JavaFX 2.2.x is not complete, and I would not recommend that you rely on it in "production" mode.
Java Client Product Management
I have a requirement to support the Khmer script, used in Cambodia, in my application. This requirement may force me to choose another technology besides JavaFX, since it is a complex script that appears to be unsupported now. Can Oracle provide any updated information on how support for these scripts are coming, and an anticipated release date?