Convert first letter into a pseudo element.

Source/core/dom/PseudoElement.h

Index: Source/core/dom/PseudoElement.h
diff --git a/Source/core/dom/PseudoElement.h b/Source/core/dom/PseudoElement.h
index db6671fa6fd5cd9b3088f8f2cead7ebca09c9ec1..6bc5111ede93a3d575a4ecb5c0376c038c35896b 100644
--- a/Source/core/dom/PseudoElement.h
+++ b/Source/core/dom/PseudoElement.h
@@ -32,12 +32,11 @@
 
 namespace blink {
 
-class PseudoElement final : public Element {
+class RenderTextFragment;
+
+class PseudoElement : public Element {
 public:
-    static PassRefPtrWillBeRawPtr<PseudoElement> create(Element* parent, PseudoId pseudoId)
-    {
-        return adoptRefWillBeNoop(new PseudoElement(parent, pseudoId));
-    }
+    static PassRefPtrWillBeRawPtr<PseudoElement> create(Element* parent, PseudoId);
 
     virtual PassRefPtr<RenderStyle> customStyleForRenderer() override;
     virtual void attach(const AttachContext& = AttachContext()) override;
@@ -49,11 +48,12 @@ public:
 
     static String pseudoElementNameForEvents(PseudoId);
 
-    void dispose();
+    virtual void dispose();
 
-private:
+protected:
     PseudoElement(Element*, PseudoId);
 
+private:
     virtual void didRecalcStyle(StyleRecalcChange) override;
 
     PseudoId m_pseudoId;
@@ -63,7 +63,19 @@ const QualifiedName& pseudoElementTagName();
 
 inline bool pseudoElementRendererIsNeeded(const RenderStyle* style)
 {
-    return style && style->display() != NONE && (style->styleType() == BACKDROP || style->contentData());
+    if (!style)
+        return false;
+    if (style->display() == NONE)
+        return false;
+
+    switch (style->styleType()) {
+    case FIRST_LETTER:
+        return true;
+    case BACKDROP:
+        return true;
+    default:

[Julien - ping for review, 2014/10/09 18:24:48]

Let's avoid having a default case as it would allow the compiler to catch adding
more cases.

[dsinclair, 2014/10/09 21:14:22]

There are a lot of these we don't actually care about (there are 21 items in the
PseudoId enum ....) most of which aren't PseudoElements (only first-letter,
backdrop, before and after).

[Julien - ping for review, 2014/10/10 14:47:07]

We looked at this with Dan and having a default with ASSERT_NOT_REACHED()
doesn't work here so it's better to revert to simple if's.

[dsinclair, 2014/10/10 18:06:52]

Done.

+        return style->contentData();
+    }
 }
 
 DEFINE_ELEMENT_TYPE_CASTS(PseudoElement, isPseudoElement());