Invalidate first line display item clients when first line style changes

third_party/WebKit/Source/core/layout/LayoutBlock.h

Index: third_party/WebKit/Source/core/layout/LayoutBlock.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.h b/third_party/WebKit/Source/core/layout/LayoutBlock.h
index d0e54aeba07150cfdeac9ed219b9e472791b3b9e..407eac137996d3d39cf7862de2600fe64855dd39 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.h
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.h
@@ -276,6 +276,23 @@ public:
     bool recalcChildOverflowAfterStyleChange();
     bool recalcOverflowAfterStyleChange();
 
+    // An example explaining layout tree structure about first-line style:

[mstensho (USE GERRIT), 2015/12/04 09:22:17]

Great!!

+    // <style>
+    //   #enclosingFirstLineStyleBlock::first-line { ... }
+    // </style>
+    // <div id="enclosingFirstLineStyleBlock">
+    //   <div>
+    //     <div id="nearestInnerBlockWithFirstLine">
+    //       [<span>]first line text[</span>]
+    //     </div>
+    //   </div>
+    // </div>
+
+    // Returns the nearest enclosing block (including this block) that contributes a first-line style to our first line.
+    LayoutBlock* enclosingFirstLineStyleBlock() const;
+    // Returns this block or the nearest inner block containing the actual first line.
+    LayoutBlockFlow* nearestInnerBlockWithFirstLine() const;
+
 protected:
     void willBeDestroyed() override;
 
@@ -396,10 +413,6 @@ private:
 
     void computeBlockPreferredLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const;
 
-    // Obtains the nearest enclosing block (including this block) that contributes a first-line style to our inline
-    // children.
-    LayoutBlock* firstLineBlock() const override;
-
     LayoutObject* hoverAncestor() const final;
     void updateDragState(bool dragOn) final;
     void childBecameNonInline(LayoutObject* child) final;