Update V8 to r7079 as required by WebKit r80534.

Change-Id: I487c152e485d5a40b68997d7c0d2f1fba5da0834
diff --git a/src/log-utils.cc b/src/log-utils.cc
index c7b7567..9a498ec 100644
--- a/src/log-utils.cc
+++ b/src/log-utils.cc
@@ -300,6 +300,8 @@
       Append("\\,");
     } else if (c == '\\') {
       Append("\\\\");
+    } else if (c == '\"') {
+      Append("\"\"");
     } else {
       Append("%lc", c);
     }