Update V8 to r4924 as required by WebKit r61871

Change-Id: Ic819dad0c1c9e035b8ffd306c96656ba87c5e85a
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index f9b20a4..b60e54d 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -552,12 +552,14 @@
     case CONS_SYMBOL_TYPE: return "CONS_SYMBOL";
     case CONS_ASCII_SYMBOL_TYPE: return "CONS_ASCII_SYMBOL";
     case EXTERNAL_ASCII_SYMBOL_TYPE:
+    case EXTERNAL_SYMBOL_WITH_ASCII_DATA_TYPE:
     case EXTERNAL_SYMBOL_TYPE: return "EXTERNAL_SYMBOL";
     case ASCII_STRING_TYPE: return "ASCII_STRING";
     case STRING_TYPE: return "TWO_BYTE_STRING";
     case CONS_STRING_TYPE:
     case CONS_ASCII_STRING_TYPE: return "CONS_STRING";
     case EXTERNAL_ASCII_STRING_TYPE:
+    case EXTERNAL_STRING_WITH_ASCII_DATA_TYPE:
     case EXTERNAL_STRING_TYPE: return "EXTERNAL_STRING";
     case FIXED_ARRAY_TYPE: return "FIXED_ARRAY";
     case BYTE_ARRAY_TYPE: return "BYTE_ARRAY";