Sampling heap profiler: Fix potential crash on accessing scripts.

src/profiler/sampling-heap-profiler.h

Index: src/profiler/sampling-heap-profiler.h
diff --git a/src/profiler/sampling-heap-profiler.h b/src/profiler/sampling-heap-profiler.h
index 0b538b070c49cdb62783ad7ced5263e05d221ebf..aa7a512664c0232a5c868071e62364a0f3cbcea2 100644
--- a/src/profiler/sampling-heap-profiler.h
+++ b/src/profiler/sampling-heap-profiler.h
@@ -110,7 +110,7 @@ class SamplingHeapProfiler {
   // loaded scripts keyed by their script id.
   v8::AllocationProfile::Node* TranslateAllocationNode(
       AllocationProfile* profile, SamplingHeapProfiler::AllocationNode* node,
-      const std::map<int, Script*>& scripts);
+      const std::map<int, Handle<Script>>& scripts);
   v8::AllocationProfile::Allocation ScaleSample(size_t size,
                                                 unsigned int count);
   AllocationNode* AddStack();