RFR: 8283063: Optimize Observable{List/Set/Map}Wrapper.retainAll/removeAll [v3]

[Michael Strauß]

> `Observable{List/Set/Map}Wrapper.retainAll/removeAll` can be optimized for some edge cases.
> 
> 1. `removeAll(c)`:
> This is a no-op if 'c' is empty.
> For `ObservableListWrapper`, returning early skips an object allocation. For `ObservableSetWrapper` and `ObservableMapWrapper`, returning early prevents an enumeration of the entire collection.
> 
> 2. `retainAll(c)`:
> This is a no-op if the backing collection is empty, or equivalent to `clear()` if `c` is empty.
> 
> I've added some tests to verify the optimized behavior for each of the three classes.

Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge branch 'master' into fixes/JDK-8283063
   
   # Conflicts:
   #	modules/javafx.base/src/main/java/com/sun/javafx/collections/ObservableListWrapper.java
   #	modules/javafx.base/src/main/java/com/sun/javafx/collections/ObservableMapWrapper.java
   #	modules/javafx.base/src/main/java/com/sun/javafx/collections/ObservableSequentialListWrapper.java
   #	modules/javafx.base/src/main/java/com/sun/javafx/collections/ObservableSetWrapper.java
 - address review comments
 - refactored removeAll/retainAll optimizations
 - Optimize removeAll/retainAll for Observable{List/Set/Map}Wrapper
 - Failing test

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Changes: https://git.openjdk.org/jfx/pull/751/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=751&range=02
  Stats: 822 lines in 11 files changed: 799 ins; 8 del; 15 mod
  Patch: https://git.openjdk.org/jfx/pull/751.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/751/head:pull/751

PR: https://git.openjdk.org/jfx/pull/751