RFR: 8288444: Remove the workaround for frame.pack() in ModalDialogTest [v3]

[Harshitha Onkar]

> Previously frame.pack() was called twice as a workaround  AWT frame sizing issue in this particular test case on Windows. This issue was fixed **[JDK-8265586](https://bugs.openjdk.org/browse/JDK-8265586)** and hence the workaround is being removed from this test.
> 
> PassFailJFrame is being used as the test framework. 
> 
> **Proposed change related to PassFailJFrame Test framework**
> 
> Instead of creating separate methods to handle AWT Windows as well as Frames, method signatures - [**PassFailJFrame.positionTestFrame()**](https://github.com/openjdk/jdk/blob/53b37fe1535388eb14e04c620a6b0118ed8884a0/test/jdk/java/awt/regtesthelpers/PassFailJFrame.java#L271) and [**PassFailJFrame.addTestFrame()**](https://github.com/openjdk/jdk/blob/53b37fe1535388eb14e04c620a6b0118ed8884a0/test/jdk/java/awt/regtesthelpers/PassFailJFrame.java#L294) can be changed to take in Window as input parameter instead of Frame, since Window is a superclass, this would allow the test frame to be a Window/Frame/Dialog and not be restricted to a Frame, additionally would allow proper disposal of windows added to the PassFailJFrame.

Harshitha Onkar has updated the pull request incrementally with one additional commit since the last revision:

  PassFailJFrame changes

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9286/files
  - new: https://git.openjdk.org/jdk/pull/9286/files/6f9e78a1..1872092e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9286&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9286&range=01-02

  Stats: 29 lines in 1 file changed: 8 ins; 4 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/9286.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9286/head:pull/9286

PR: https://git.openjdk.org/jdk/pull/9286