Change Font::offsetForPositionForComplexText to use CachingWordShapeIterator

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index 17a9d21619a15113e923876fbde96792a59b2e31..c5f2099278bea5d0a6811f778e372615db368115 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -662,6 +662,15 @@ crbug.com/467477 fast/multicol/vertical-rl/nested-columns.html [ ImageOnlyFailur
 
 crbug.com/506525 [ XP ] paint/masks/fieldset-mask.html [ ImageOnlyFailure ]
 
+crbug.com/422670 [ Mac ] editing/selection/vertical-rl-rtl-extend-line-backward-br.html [ NeedsRebaseline ]
+crbug.com/422670 [ Mac ] editing/selection/vertical-rl-rtl-extend-line-backward-p.html [ NeedsRebaseline ]
+crbug.com/422670 [ Mac ] editing/selection/vertical-rl-rtl-extend-line-forward-br.html [ NeedsRebaseline ]
+crbug.com/422670 [ SnowLeopard Lion MountainLion Mavericks ] editing/selection/vertical-rl-rtl-extend-line-forward-p.html [ NeedsRebaseline ]
+crbug.com/422670 [ Linux ] fast/text/emphasis-ellipsis-complextext.html [ NeedsRebaseline ]
+crbug.com/422670 [ Mac ] fast/css/vertical-text-overflow-ellipsis-text-align-center.html [ NeedsRebaseline ]
+crbug.com/422670 [ Linux Mac ] fast/css/vertical-text-overflow-ellipsis-text-align-left.html [ NeedsRebaseline ]
+crbug.com/422670 [ Linux ] fast/text/international/draw-complex-text-from-to.html [ NeedsRebaseline ]
+
 crbug.com/400841 media/video-canvas-draw.html [ ImageOnlyFailure ]
 crbug.com/400829 media/video-object-fit.html [ ImageOnlyFailure ]
 crbug.com/400829 virtual/stable/media/stable/video-object-fit-stable.html [ ImageOnlyFailure ]