<Swing Dev> [14] RFR JDK-8233634:TESTBUG] Swing text test bug4278839.java fails on macos

[Prasanta Sadhukhan]

Hi All,

Please review a fix for a test issue seen in mach5 macos system where 
the test fails intermittently.

The test creates a textarea and populates with strings and test cursor 
movement between words
by pressing RIGHT key to move right of each word to go to the end of 
textarea and then press LEFT key to move left of each word and reach at 
0th position of the textarea.
However, sometimes due to idiosyncrasies of other test, the caret at the 
beginning of test is not at the start (ie 0th position) of the text so 
moving 1st RIGHT does not end the caret at the 1st position, so
moveCaret(true) == 1 kind of check fails.

Proposed fix is to ensure the caret is always at the beginning (ie 0th 
location) of the textarea. Also, ensured the frame is disposed at end of 
test and increased robot autodelay a bit.

Tested several times in mach5 on all 3 platforms whose link can be seen 
in JBS.

Bug: https://bugs.openjdk.java.net/browse/JDK-8233634

webrev: http://cr.openjdk.java.net/~psadhukhan/8233634/webrev.0/

Regards
Prasanta