Add a version tag for cached data.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index c7ebc7714f57a052f99964e44e412a2d66770c7d..9a1ff600745869f079c186ee3b8d2e077a713809 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -14,6 +14,7 @@
 #include "include/v8-testing.h"
 #include "src/assert-scope.h"
 #include "src/background-parsing-task.h"
+#include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/time.h"
 #include "src/base/utils/random-number-generator.h"
@@ -1846,6 +1847,13 @@ Local<Script> ScriptCompiler::Compile(Isolate* v8_isolate,
 }
 
 
+uint32_t ScriptCompiler::CachedDataVersionTag() {
+  return static_cast<uint32_t>(base::hash_combine(
+      internal::Version::Hash(), internal::FlagList::Hash(),
+      static_cast<uint32_t>(internal::CpuFeatures::SupportedFeatures())));
+}
+
+
 Local<Script> Script::Compile(v8::Handle<String> source,
                               v8::ScriptOrigin* origin) {
   i::Handle<i::String> str = Utils::OpenHandle(*source);