Make first-letter style to work with editing

LayoutTests/editing/selection/caret-with-first-letter-expected.txt

Index: LayoutTests/editing/selection/caret-with-first-letter-expected.txt
diff --git a/LayoutTests/editing/selection/caret-with-first-letter-expected.txt b/LayoutTests/editing/selection/caret-with-first-letter-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..b73e92e72ffbd82b24eb9d5788aa4a391d1e9246
--- /dev/null
+++ b/LayoutTests/editing/selection/caret-with-first-letter-expected.txt
@@ -0,0 +1,24 @@
+Move caret before first letter
+PASS selection.type is "Caret"
+PASS selection.anchorNode is test.firstChild
+PASS selection.anchorOffset is 0
+Hit right arrow key
+PASS selection.type is "Caret"
+PASS selection.anchorNode is test.firstChild
+PASS selection.anchorOffset is 1
+Hit right arrow key
+PASS selection.type is "Caret"
+PASS selection.anchorNode is test.firstChild
+PASS selection.anchorOffset is 2
+Hit left arrow key
+PASS selection.type is "Caret"
+PASS selection.anchorNode is test.firstChild
+FAIL selection.anchorOffset should be 1. Was 3.
+Hit left arrow key
+PASS selection.type is "Caret"
+PASS selection.anchorNode is test.firstChild
+FAIL selection.anchorOffset should be 0. Was 4.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+