RFR: JDK-8297413: Remove easy warnings in javafx.graphics

[John Hendrikx]

- 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

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Commit messages:
 - Remove unused imports
 - Remove unused SuppressWarnings
 - Remove declared checked exceptions that are never thrown
 - Remove redundant super interface
 - Remove redundant type arguments in CssParser
 - Remove unnecessary casts
 - Remove unused type parameter
 - Remove non-standard SuppressWarnings tokens
 - Use diamond operator
 - Remove unnecessary semi-colons and add override annotations

Changes: https://git.openjdk.org/jfx/pull/960/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=960&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297413
  Stats: 3220 lines in 619 files changed: 1253 ins; 459 del; 1508 mod
  Patch: https://git.openjdk.org/jfx/pull/960.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/960/head:pull/960

PR: https://git.openjdk.org/jfx/pull/960