RFR: JDK-8297414: Remove easy warnings in javafx.controls [v8]

[John Hendrikx]

> Note: I ran into a `javac` compiler bug while replacing types with diamond operators (ecj has no issues).  I had two options, add a `SuppressWarnings("unused")` or to use a lambda instead of a method reference to make `javac` happy.  I choose the later and added a comment so it can be fixed once the bug is fixed.  I've reported the issue here: https://bugs.openjdk.org/browse/JDK-8297428
> 
> - Remove unsupported/unnecessary SuppressWarning annotations
> - Remove reduntant type specifications (use diamond operator)
> - Remove unused or duplicate imports
> - Remove unnecessary casts (type is already correct type or can be autoboxed)
> - Remove unnecessary semi-colons (at end of class definitions, or just repeated ones)
> - Remove redundant super interfaces (interface that is already inherited)
> - Remove unused type parameters
> - Remove declared checked exceptions that are never thrown
> - Add missing `@Override` annotations

John Hendrikx has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 23 commits:

 - Merge branch 'master' of https://git.openjdk.org/jfx into feature/fix-easy-warnings-in-controls
 - Fix some indents and put declarations on one line where possible
 - Replace StubToolkit casts with asserts (2)
 - Revert read only property instanceof checks
   
   Added SuppressWarnings("cast") as these checks should be retained
 - Replace StubToolkit casts with asserts
 - Revert instanceof changes and replace with null checks
 - Revert "Fix warnings in fxml"
   
   This reverts commit b148aa3cc8a4676167a9eb8a023cddce3de116e7.
 - Fix warnings in fxml
 - Add workaround for JDK-8297428 (javac compiler type inference bug)
 - Remove unused imports
 - ... and 13 more: https://git.openjdk.org/jfx/compare/fbad15d1...1697bd1d

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Changes: https://git.openjdk.org/jfx/pull/959/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=959&range=07
  Stats: 2294 lines in 319 files changed: 159 ins; 305 del; 1830 mod
  Patch: https://git.openjdk.org/jfx/pull/959.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/959/head:pull/959

PR: https://git.openjdk.org/jfx/pull/959