Corrections for Javadoc

[Nir Lisker]

I'm looking at build 168 of JDK9 and there are a few mistakes in the docs.
I can't submit issues to the JIRA so I'll list them here. A similar issue
was https://bugs.openjdk.java.net/browse/JDK-8177341.


   - The following use "a Observable..." instead of "an Observable...".
   - javafx.beans.property
         - ListProperty<E>
         - MapProperty<K,V>
         - ReadOnlyListPropertyBase<E>
         - SetProperty<E>
      - javafx.beans.binding
         - NumberExpression
         - BooleanExpression
         - DoubleExpression
         - FloatExpression
         - IntegerExpression
         - ListExpression
         - LongExpression
         - MapExpression
         - ObjectExpression
         - SetExpression
         - StringExpression
         - javafx.scene.shape.ObservableFaceArray copies its description
   from its superinteface ObservableIntegerArray, does not declare any API
   methods and is listed under package javafx.scene.shape. It's not clear at
   all what this interface is. As it is, it looks like it's not meant to be
   exposed.
   - javafx.collections.ObservableIntegerArray uses "a int[]" instead of
   "an int[]". This writing ("a int") is found in java.lang.Integer as well in
   a few places.

Nir