Elements whose contents start with an astral Unicode symbol disappear when CSS `::first-letter` is …

Source/core/dom/FirstLetterPseudoElement.cpp

Index: Source/core/dom/FirstLetterPseudoElement.cpp
diff --git a/Source/core/dom/FirstLetterPseudoElement.cpp b/Source/core/dom/FirstLetterPseudoElement.cpp
index d47a521eba3c9acb4c8cc2dc9c3489c14df10b4c..082e5da9268bae51b18151f19a8de542960e8204 100644
--- a/Source/core/dom/FirstLetterPseudoElement.cpp
+++ b/Source/core/dom/FirstLetterPseudoElement.cpp
@@ -30,6 +30,7 @@
 #include "core/layout/LayoutObjectInlines.h"
 #include "core/layout/LayoutText.h"
 #include "core/layout/LayoutTextFragment.h"
+#include "platform/text/TextBreakIterator.h"
 #include "wtf/TemporaryChange.h"
 #include "wtf/text/WTFString.h"
 #include "wtf/unicode/icu/UnicodeIcu.h"
@@ -77,7 +78,11 @@ unsigned FirstLetterPseudoElement::firstLetterLength(const String& text)
         return 0;
 
     // Account the next character for first letter.
-    length++;
+    String substring = text.substring(length);
+    const bool is8Bit = substring.is8Bit();
+    if (is8Bit)
+        substring = String::make16BitFrom8BitSource(text.substring(length).characters8(), substring.length());
+    length += countCharactersAndGraphemesInCluster(substring.characters16(), substring.length(), 0, 1).characters;

[changseok, 2015/06/01 17:47:47]

Here the endIndex 1 doesn't work for a special character. It should be 2 but I
don't know how I get it or where I can get it from.. 

 
     // Keep looking for allowed punctuation for the :first-letter.
     for (; length < textLength; ++length) {