[jfx20] RFR: 8301832: InputMethodEvents are not enabled for text input controls

[Andy Goryachev]

A fix for regression introduced by [JDK-8268877](https://bugs.openjdk.org/browse/JDK-8268877).

For IME to work, both `setOnInputMethodTextChanged()` and `setInputMethodRequests()` needs to be set, see Scene:2242.

The fix involves changing the code back to setting the control properties and doing so in the install() method.

Thank you Martin Fox (@beldenfox ?) for noticing the issue!

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Commit messages:
 - 8301832: InputMethodEvents are not enabled for text input controls

Changes: https://git.openjdk.org/jfx/pull/1024/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1024&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301832
  Stats: 14 lines in 1 file changed: 10 ins; 4 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1024.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1024/head:pull/1024

PR: https://git.openjdk.org/jfx/pull/1024