[CSS Grid Layout] Ignore ::first-letter pseudo-element

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index 4da89dedae2755cf9f5fa57fae19ab65d1b7e706..f78f440c07e86e1768b2eea2967befc172a87ecd 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -3923,6 +3923,17 @@ int RenderBlock::lastLineBoxBaseline(LineDirectionMode lineDirection) const
     return -1;
 }
 
+static inline bool isRenderBlockFlowOrRenderButton(RenderObject* renderObject)
+{
+    // We include isRenderButton in this check because buttons are implemented
+    // using flex box but should still support first-line|first-letter.
+    // The flex box and grid specs require that flex box and grid do not
+    // support first-line|first-letter, though.
+    // FIXME: Remove when buttons are implemented with align-items instead
+    // of flex box.
+    return renderObject->isRenderBlockFlow() || renderObject->isRenderButton();
+}
+
 RenderBlock* RenderBlock::firstLineBlock() const
 {
     RenderBlock* firstLineBlock = const_cast<RenderBlock*>(this);
@@ -3932,15 +3943,9 @@ RenderBlock* RenderBlock::firstLineBlock() const
         if (hasPseudo)
             break;
         RenderObject* parentBlock = firstLineBlock->parent();
-        // We include isRenderButton in this check because buttons are
-        // implemented using flex box but should still support first-line. The
-        // flex box spec requires that flex box does not support first-line,
-        // though.
-        // FIXME: Remove when buttons are implemented with align-items instead
-        // of flexbox.
         if (firstLineBlock->isReplaced() || firstLineBlock->isFloating()
             || !parentBlock
-            || (!parentBlock->isRenderBlockFlow() && !parentBlock->isRenderButton()))
+            || !isRenderBlockFlowOrRenderButton(parentBlock))
             break;
         ASSERT_WITH_SECURITY_IMPLICATION(parentBlock->isRenderBlock());
         if (toRenderBlock(parentBlock)->firstChild() != firstLineBlock)
@@ -3986,21 +3991,15 @@ static inline RenderObject* findFirstLetterBlock(RenderBlock* start)
 {
     RenderObject* firstLetterBlock = start;
     while (true) {
-        // We include isRenderButton in these two checks because buttons are
-        // implemented using flex box but should still support first-letter.
-        // The flex box spec requires that flex box does not support
-        // first-letter, though.
-        // FIXME: Remove when buttons are implemented with align-items instead
-        // of flexbox.
         bool canHaveFirstLetterRenderer = firstLetterBlock->style()->hasPseudoStyle(FIRST_LETTER)
             && firstLetterBlock->canHaveGeneratedChildren()
-            && (!firstLetterBlock->isFlexibleBox() || firstLetterBlock->isRenderButton());
+            && isRenderBlockFlowOrRenderButton(firstLetterBlock);
         if (canHaveFirstLetterRenderer)
             return firstLetterBlock;
 
         RenderObject* parentBlock = firstLetterBlock->parent();
         if (firstLetterBlock->isReplaced() || !parentBlock
-            || (!parentBlock->isRenderBlockFlow() && !parentBlock->isRenderButton())) {
+            || !isRenderBlockFlowOrRenderButton(parentBlock)) {
             return 0;
         }
         ASSERT(parentBlock->isRenderBlock());
@@ -4183,7 +4182,7 @@ void RenderBlock::updateFirstLetter()
         }
     }
 
-    if (!currChild)
+    if (!currChild || !isRenderBlockFlowOrRenderButton(firstLetterBlock))
         return;
 
     // If the child already has style, then it has already been created, so we just want