RFR: JDK-8257086: Clarify differences between {Float, Double}.equals and == [v4]

[Joe Darcy]

> Updates to the specifications of Double.{equals, compareTo} to explain more explicitly why the obvious wrappers around "==" and "<"/"==" are not sufficient for floating-point values.
> 
> Once the wording is worked out, I'll replicate it for the analogous methods on Float.

Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:

  Editing pass on changes in Double; add accommodations in Float.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1699/files
  - new: https://git.openjdk.java.net/jdk/pull/1699/files/9d80e279..072c40d9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1699&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1699&range=02-03

  Stats: 78 lines in 2 files changed: 18 ins; 15 del; 45 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1699.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1699/head:pull/1699

PR: https://git.openjdk.java.net/jdk/pull/1699