RFR: 8263102: Expand documention of Method.isBridge

[Joe Darcy]

The existing documentation of Method.isBridge isn't terribly helpful to the reader. This RFE proposes to given a common example of how bridge methods are used. The JLS does *not* have a section discussing bridge methods in detail; bridge methods are a compilation technique for lowering the Java language to the JVM, they are not a language feature per se. The example given is not exhaustive; there can be and are other uses of bridge methods.

Once the text is agreed to; I'll update the copyright year as well.

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Commit messages:
 - Fix trailing white space.
 - Rewording.
 - Update wording.
 - 8263102: Expand documention of Method.isBridg

Changes: https://git.openjdk.java.net/jdk/pull/2852/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2852&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263102
  Stats: 34 lines in 1 file changed: 30 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2852.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2852/head:pull/2852

PR: https://git.openjdk.java.net/jdk/pull/2852