Make first-letter style to work with editing

Source/core/editing/htmlediting.cpp

Index: Source/core/editing/htmlediting.cpp
diff --git a/Source/core/editing/htmlediting.cpp b/Source/core/editing/htmlediting.cpp
index 858d2e4a51e38575cdd74a96aad6ef3aa0aaad5c..5b6301b067ce55a694b373531cfdce9732f44782 100644
--- a/Source/core/editing/htmlediting.cpp
+++ b/Source/core/editing/htmlediting.cpp
@@ -51,6 +51,7 @@
 #include "core/html/HTMLUListElement.h"
 #include "core/page/Frame.h"
 #include "core/rendering/RenderObject.h"
+#include "core/rendering/RenderText.h"
 #include "wtf/Assertions.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/text/StringBuilder.h"
@@ -971,7 +972,11 @@ int caretMinOffset(const Node* n)
 {
     RenderObject* r = n->renderer();
     ASSERT(!n->isCharacterDataNode() || !r || r->isText()); // FIXME: This was a runtime check that seemingly couldn't fail; changed it to an assertion for now.
-    return r ? r->caretMinOffset() : 0;
+    if (!r)
+        return 0;
+    if (r->isText())
+        return r->caretMinOffset() + toRenderText(r)->textStartOffset();
+    return r->caretMinOffset();
 }
 
 // If a node can contain candidates for VisiblePositions, return the offset of the last candidate, otherwise
@@ -979,8 +984,9 @@ int caretMinOffset(const Node* n)
 int caretMaxOffset(const Node* n)
 {
     // For rendered text nodes, return the last position that a caret could occupy.
-    if (n->isTextNode() && n->renderer())
-        return n->renderer()->caretMaxOffset();
+    RenderObject* renderer = n->renderer();
+    if (renderer && renderer->isText())
+        return renderer->caretMaxOffset() + toRenderText(renderer)->textStartOffset();
     // For containers return the number of children. For others do the same as above.
     return lastOffsetForEditing(n);
 }