[LayoutNG] Skip marker while FirstLetterPseudoElement find first letter

Like legacy layout, skip list marker while finding the first letter.

Bug: 725277
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I467c766f8e362f7e12b8d9c7b0251fee02e1b0a2
Reviewed-on: https://chromium-review.googlesource.com/1156111
Commit-Queue: cathie chen <cathiechen@tencent.com>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580202}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -428,7 +428,6 @@ crbug.com/591099 fast/css/outline-narrowLine.html [ Failure ]
 crbug.com/591099 fast/css/transform-inline-style-remove.html [ Failure ]
 crbug.com/591099 fast/css3-text/css3-text-decoration/text-underline-position/text-underline-position-under.html [ Failure ]
 crbug.com/591099 fast/dom/nodesFromRect/nodesFromRect-basic.html [ Failure ]
-crbug.com/591099 fast/dynamic/first-letter-after-list-marker.html [ Failure ]
 crbug.com/591099 fast/events/touch/compositor-touch-hit-rects.html [ Failure ]
 crbug.com/591099 fast/events/wheel/mainthread-touchpad-fling-latching.html [ Pass ]
 crbug.com/591099 fast/events/wheel/wheel-scroll-latching-on-scrollbar.html [ Pass ]

third_party/WebKit/LayoutTests/flag-specific/enable-blink-features=LayoutNG/fast/dynamic/first-letter-after-list-marker-expected.txt

+layer at (0,0) size 800x600
+  LayoutView at (0,0) size 800x600
+layer at (0,0) size 800x600
+  LayoutNGBlockFlow {HTML} at (0,0) size 800x600
+    LayoutNGBlockFlow {BODY} at (8,8) size 784x492
+      LayoutNGBlockFlow {UL} at (0,0) size 784x100
+        LayoutNGListItem {LI} at (40,0) size 744x100
+          LayoutNGListMarker (anonymous) at (-61,0) size 29x100
+            LayoutText (anonymous) at (0,0) size 29x100
+              text run at (0,0) width 29: "\x{2022} "
+          LayoutInline {<pseudo:first-letter>} at (0,0) size 100x100 [color=#008000]
+            LayoutTextFragment (anonymous) at (0,0) size 100x100
+              text run at (0,0) width 100: "a"
+          LayoutTextFragment {#text} at (0,0) size 0x0

third_party/blink/renderer/core/dom/first_letter_pseudo_element.cc

@@ -31,6 +31,7 @@
 #include "third_party/blink/renderer/core/layout/layout_object_inlines.h"
 #include "third_party/blink/renderer/core/layout/layout_text.h"
 #include "third_party/blink/renderer/core/layout/layout_text_fragment.h"
+#include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_item.h"
 #include "third_party/blink/renderer/platform/text/text_break_iterator.h"
 #include "third_party/blink/renderer/platform/wtf/text/unicode.h"
 #include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
@@ -113,6 +114,10 @@ LayoutText* FirstLetterPseudoElement::FirstLetterTextLayoutObject(
       !parent_layout_object->BehavesLikeBlockContainer())
     return nullptr;
 
+  LayoutObject* marker =
+      parent_layout_object->IsLayoutNGListItem()
+          ? ToLayoutNGListItem(parent_layout_object)->Marker()
+          : nullptr;
   // Drill down into our children and look for our first text child.
   LayoutObject* first_letter_text_layout_object =
       parent_layout_object->SlowFirstChild();
@@ -139,7 +144,8 @@ LayoutText* FirstLetterPseudoElement::FirstLetterTextLayoutObject(
         break;
       first_letter_text_layout_object =
           first_letter_text_layout_object->NextSibling();
-    } else if (first_letter_text_layout_object->IsListMarker()) {
+    } else if (first_letter_text_layout_object->IsListMarker() ||
+               first_letter_text_layout_object == marker) {
       first_letter_text_layout_object =
           first_letter_text_layout_object->NextSibling();
     } else if (first_letter_text_layout_object
@@ -170,6 +176,9 @@ LayoutText* FirstLetterPseudoElement::FirstLetterTextLayoutObject(
       // setting up the first letter then.
       return nullptr;
     } else {
+      if (first_letter_text_layout_object->IsLayoutNGListItem())
+        marker = ToLayoutNGListItem(first_letter_text_layout_object)->Marker();
+
       first_letter_text_layout_object =
           first_letter_text_layout_object->SlowFirstChild();
     }