Set selection to INPUT/TEXTAREA before dispatching 'focus' event.

third_party/WebKit/LayoutTests/fast/forms/selection-functions-expected.txt

 This test checks if setSelectionRange(), selectionStart, and selectionEnd on a textarea and input work as expected. This includes checking edge cases such as out-of-bound values.
 
 If this test passed you'll see a bunch of correct selection ranges below. Check the expected file for the correct ranges.
 
     
 ===textarea===
 setSelectionRange():
 3, 7
 0, 5
 42, 48
 2, 2
 
 selectionStart:
 3, 3
 7, 7
 0, 7
 48, 48
 3, 48
 
 selectionEnd:
 3, 5
 2, 2
 0, 0
 0, 48
 7, 7
 
+selectionStart and selectionEnd in focus handler don't return wrong values 0,0:
+7, 7
+
 ===input===
 setSelectionRange():
 3, 7
 0, 5
 42, 48
 2, 2
 
 selectionStart:
 3, 3
 7, 7
 0, 7
 48, 48
 3, 48
 
 selectionEnd:
 3, 5
 2, 2
 0, 0
 0, 48
 7, 7
 
+selectionStart and selectionEnd in focus handler don't return wrong values 0,0:
+7, 7
+
 ===button===
 button.selectionStart threw exception
 button.selectionStart = 0 threw exception
 button.selectionEnd threw exception
 button.selectionEnd = 0 threw exception
 button.setSelectionRange defined
 button.setSelectionRange(0,0) threw exception