Make select drop down popup RTL aware

This CL puts a vertical scrollbar on the left if dir="RTL"
for select drop-down list popups. Select menu list popups use
PopupListBox which is derived from ScrollView. ScrollView
places the vertical scrollbar always on right. Changes in
ScrollView.cpp places the vertical scrollbar on left if
shouldPlaceVerticalScrollbarOnLeft() is true.

Scrollbars on iframe (crbug.com/250514) and main frame
(viewport) outermost scrollbars (crbug.com/249860) are also
placed by ScrollView but shouldPlaceVerticalScrollbarOnLeft()
returns false so this CL does not alter the scrollbar
placement for iframe and main frame.

PopupListBox::shouldPlaceVerticalScrollbarOnLeft() returns
true if dir="RTL", so vertical scrollbar appears on left
for select menu list box. And the changes in
FramelessScrollView.cpp and PopupListBox.cpp is required
to move the windowClipRect and contents after the
scrollbar respectively.

BUG=269164

Review URL: https://codereview.chromium.org/59333002

git-svn-id: svn://svn.chromium.org/blink/trunk@161944 bbb929c8-8fbe-4397-9dbb-9b2b20218538