Merge 84005 - Mac. Ensure no more than one visibly selected item in each bookmark folder menu.

Merge 84005 - Mac. Ensure no more than one visibly selected item in each bookmark folder menu.  

Make the BookmarkBarFolderButtonCell not hover select itself (by overriding setMouseInside to do nothing). Instead have the controller manage the selection, which enables selection to be moved from the keyboard or mouse without two selections appearing.

Remove the [BookmarkBarFolderController toggleButtonBorderingWhileMouseInside] hack which was only necessary because of a bug in [GradientButtonCell updateTrackingAreas] that unexpectedly changed the isMouseInside_ state.

Add new logic to [BookmarkBarFolderController performOneScroll] to make it detect an existing mouse-initiated selection. If one is present before scroll it will select whatever item ends up under the mouse after the scroll. Otherwise no selection change will happen, which is right.

BUG=75014, 77676, 80043, 81072, 46595
Review URL: http://codereview.chromium.org/6889025

TBR=maf@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=84010