[AC-1779] U/I objects not collected with GC. (memory leak?)

U/I objects that changed visibility after displayed (or in "postlayout" event) are not collected with GC. I attached test code and pictures (object hisotgram in heap analyzed with MAT). *histogram filterd with "^ti.*ui.*". 1) Start test code and open DDMS, select test code process and click "Update heap" button. 2) In Heap tab, click "Cause GC" button a few times. 3) Click "Dump HPROF file" button, and get object hisotgram with MAT. <- Objects#0 column 4) Click menu button in Android emulator, do "update!" command 5 times. 5) In Heap tab, click "Cause GC" button a few times. 6) Click "Dump HPROF file" button, and get object hisotgram with MAT. <- Objects#1 column 7) Click menu button in Android emulator, do "update!" command 5 times. 8) Repeat 10 times above (to Object#9). pic01.png - attached test code's result. pic02.png - attached test code + "commented out part" in "postlayout" event handler. In addition, visibility changed with table's click handler, also increased memory allocation.