Un-insanify first-letter handling in TextIterator (to some degree)

third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt

Index: third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt
diff --git a/third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt b/third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt
index 5873f9e8b03c0bb8fdbf8c6a77981ab1eb066b67..f2fc4e191a791b11f8c31c7faeb27e1e1e88eb51 100644
--- a/third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt
+++ b/third_party/WebKit/LayoutTests/accessibility/first-letter-text-transform-causes-crash-expected.txt
@@ -9,7 +9,7 @@ On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE
 AXRole: AXWebArea
     AXRole: AXDescriptionListTerm
         AXRole: AXStaticText "Dt"
-            AXRole: AXInlineTextBox "Dt"

[Xiaocheng, 2017/05/16 03:50:06]

dmazzoni@: Is it that AX is depending on incorrect behavior of TextIterator?

When with first-letter, AXInlineTextBox seems to hold only the text box of
first-letter. Before this patch, TextIterator cannot correctly stop inside
first-letter, so it emits "Dt" even if the given range is just "D" (the
first-letter).

With the patch, TextIterator only emits "D" when the given range is the
first-letter. However, it makes the AX tree dump look wrong...

[dmazzoni, 2017/05/16 16:01:15]

Happy to have this fixed!

+            AXRole: AXInlineTextBox "D"
     AXRole: AXParagraph
         AXRole: AXStaticText "End of test"
 PASS successfullyParsed is true