[RTL, Regression] RTL orientation, on ColorPicker palette popup, wrong position of the floating window for selected color.

Steps to reproduce:
1. Set the node orientation of a ColorPicker to RTL
2. Click the ColorPicker, the ColorPicker palette is popped up.

Bug:
1. the floating window for selected color(default is white) is placed at the left side of the palette, it's not over the "white" color in the palette.
2. hovering mouse on the palette from right to left, the floating window moves from left to right, and vice versa.
3. press left arrow key on the palette, the the floating window moves from left to right, and vice versa.

These behaviors didn't happen with 8.0. It's only reproducible with 8u20.