[Turbofan] Don't inline if we never saw a function.

src/feedback-vector.cc

Index: src/feedback-vector.cc
diff --git a/src/feedback-vector.cc b/src/feedback-vector.cc
index 4003068e9b5960e7af1b332c2b926abd9b5c68ba..5d842763994c75d047839b9423b2d2be298b744d 100644
--- a/src/feedback-vector.cc
+++ b/src/feedback-vector.cc
@@ -591,6 +591,10 @@ int CallICNexus::ExtractCallCount() {
 float CallICNexus::ComputeCallFrequency() {
   double const invocation_count = vector()->invocation_count();
   double const call_count = ExtractCallCount();
+  if (invocation_count == 0) {
+    // Prevent division by 0.
+    return 0.0f;
+  }
   return static_cast<float>(call_count / invocation_count);
 }