Use correct offset when attribute auto is present

LayoutTests/editing/selection/caret-in-textarea-auto-expected.txt

Index: LayoutTests/editing/selection/caret-in-textarea-auto-expected.txt
diff --git a/LayoutTests/editing/selection/caret-in-textarea-auto-expected.txt b/LayoutTests/editing/selection/caret-in-textarea-auto-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..70a61bed3151bb7b4bf9b4ce226790fce5d8f56a
--- /dev/null
+++ b/LayoutTests/editing/selection/caret-in-textarea-auto-expected.txt
@@ -0,0 +1,23 @@
+layer at (0,0) size 800x600
+  RenderView at (0,0) size 800x600
+layer at (0,0) size 800x155
+  RenderBlock {HTML} at (0,0) size 800x155
+    RenderBody {BODY} at (8,16) size 784x131
+      RenderBlock {P} at (0,0) size 784x40
+        RenderText {#text} at (0,0) size 781x39
+          text run at (0,0) width 781: "This tests that typing in a textarea with direction auto and having RTL text. When entering a LTR text caret position is changed. To"
+          text run at (0,20) width 679: "test manually, click at the end of RTL text and press enter. Then enter text, caret should move along with the text."
+      RenderBlock (anonymous) at (0,56) size 784x75
+        RenderText {#text} at (0,0) size 0x0
+        RenderText {#text} at (0,0) size 0x0
+        RenderText {#text} at (0,0) size 0x0
+layer at (8,74) size 202x66 clip at (9,75) size 200x64
+  RenderTextControl {TEXTAREA} at (0,2) size 202x66 [bgcolor=#FFFFFF] [border: (1px solid #000000)]
+    RenderBlock {DIV} at (11,11) size 180x44
+      RenderText {#text} at (156,0) size 24x22
+        text run at (156,0) width 24 RTL: "\x{5D0}!"
+      RenderText {#text} at (156,0) size 0x22
+        text run at (156,0) width 0 RTL: " "
+      RenderText {#text} at (0,22) size 72x22
+        text run at (0,22) width 72: "hello!"
+caret: position 6 of child 2 {#text} of child 0 {DIV} of {#document-fragment} of child 3 {TEXTAREA} of body