Cleanup native, collected, and stub code handling in profiler

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index faf01cc65881fe6f86a4146bace35aba588d06a1..ac24661530a990e433632379eaa01e07ef007383 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -3275,12 +3275,38 @@ class Code : public Object {
     StorePointer(&raw_ptr()->exception_handlers_, handlers.raw());
   }
 
+  bool OwnerIsFunction() const {
+    return raw_ptr()->owner_->IsHeapObject();
+  }
+
+  bool OwnerIsNotNullFunction() const {
+    return (raw_ptr()->owner_->IsHeapObject()) &&
+           (raw_ptr()->owner_ != Function::null());
+  }
+
+  bool OwnerIsAllocationStub() const {
+    return !raw_ptr()->owner_->IsHeapObject();
+  }
+
   RawFunction* function() const {
-    return raw_ptr()->function_;
+    ASSERT(OwnerIsFunction());
+    return reinterpret_cast<RawFunction*>(raw_ptr()->owner_);
+  }
+
+  RawSmi* allocation_stub_class_id() const {
+    ASSERT(OwnerIsAllocationStub());
+    return reinterpret_cast<RawSmi*>(raw_ptr()->owner_);
   }
-  void set_function(const Function& function) const {
+
+  void set_owner_function(const Function& function) const {
     ASSERT(function.IsOld());
-    StorePointer(&raw_ptr()->function_, function.raw());
+    StorePointer(&raw_ptr()->owner_,
+                 reinterpret_cast<RawObject*>(function.raw()));
+  }
+
+  void set_owner_allocation_stub_class_id(RawSmi* cid) const {
+    ASSERT(!cid->IsHeapObject());
+    raw_ptr()->owner_ = reinterpret_cast<RawObject*>(cid);
   }
 
   // We would have a VisitPointers function here to traverse all the
@@ -3305,6 +3331,7 @@ class Code : public Object {
                                Assembler* assembler,
                                bool optimized = false);
   static RawCode* LookupCode(uword pc);
+  static RawCode* LookupCodeInVmIsolate(uword pc);
 
   int32_t GetPointerOffsetAt(int index) const {
     return *PointerOffsetAddrAt(index);
@@ -3383,6 +3410,7 @@ class Code : public Object {
   }
 
   intptr_t BinarySearchInSCallTable(uword pc) const;
+  static RawCode* LookupCodeInIsolate(Isolate* isolate, uword pc);
 
   // New is a private method as RawInstruction and RawCode objects should
   // only be created using the Code::FinalizeCode method. This method creates
@@ -4937,6 +4965,7 @@ class String : public Instance {
           ch_(0),
           index_(-1),
           end_(str.Length()) {
+      ASSERT(!str_.IsNull());
     }
 
     CodePointIterator(const String& str, intptr_t start, intptr_t length)