Update V8 to r4730 as required by WebKit r60469
diff --git a/src/version.cc b/src/version.cc
index 1bf543d..adeee59 100644
--- a/src/version.cc
+++ b/src/version.cc
@@ -34,7 +34,7 @@
 // cannot be changed without changing the SCons build script.
 #define MAJOR_VERSION     2
 #define MINOR_VERSION     2
-#define BUILD_NUMBER      10
+#define BUILD_NUMBER      12
 #define PATCH_LEVEL       0
 #define CANDIDATE_VERSION false