Cache optimized code on shared function info.

src/runtime-profiler.cc

Index: src/runtime-profiler.cc
diff --git a/src/runtime-profiler.cc b/src/runtime-profiler.cc
index c6e2b465892b4d6e7c0242ec86bc1c9cdf9a6a44..2724230c4b4dc313175a6b3d10afe7bdd7234a4e 100644
--- a/src/runtime-profiler.cc
+++ b/src/runtime-profiler.cc
@@ -217,7 +217,10 @@ int RuntimeProfiler::LookupSample(JSFunction* function) {
   for (int i = 0; i < kSamplerWindowSize; i++) {
     Object* sample = sampler_window_[i];
     if (sample != NULL) {
-      if (function == sample) {
+      bool fits = FLAG_lookup_sample_by_shared
+          ? (function->shared() == JSFunction::cast(sample)->shared())
+          : (function == JSFunction::cast(sample));
+      if (fits) {
         weight += sampler_window_weight_[i];
       }
     }