Fix clientLeft value for RTL direction, while the element have vertical scrollbar in left side.

LayoutTests/scrollbars/rtl/div-horizontal-with-vertical-scrollbar-expected.txt

 Test that horizontal scrollbar should appear as the content width encroaches upon the vertical scrollbar and also test if WebKit can show the left side of the inner elements regardless of the position of its scrollbars. To test manually, open this document and verify we can see "ABC" both in the LTR element and in the RTL element.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
 Verify the widths of the outer RTL elements are the same as the widths of the outer LTR elements.
 PASS outerLTR.offsetWidth == outerRTL.offsetWidth is true
 PASS outerLTR.clientWidth == outerRTL.clientWidth is true
 PASS outerLTR.scrollWidth == outerRTL.scrollWidth is true
 Verify the widths of the inner RTL elements are the same as the widths of the inner LTR elements.
 PASS innerLTR.offsetWidth == innerRTL.offsetWidth is true
 PASS innerLTR.clientWidth == innerRTL.clientWidth is true
 PASS innerLTR.scrollWidth == innerRTL.scrollWidth is true
 Verify the width of the vertical scrollbar of the outer RTL element is the same as the one of the outer LTR element regardless of their scrollbar positions.
 PASS scrollbarWidthLTR == scrollbarWidthRTL is true
+PASS outerRTL.clientLeft == scrollbarWidthRTL is true
 PASS successfullyParsed is true
 
 TEST COMPLETE
 ABC
 ABC