[Interpreter] Add IsInterpreted() to JSFunction and use to fix test-heap tests.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 25fdb80915346ed079062b81da68e3c9b7013e36..cfc2d12ad1ffeead5cfbab9390acb701aac40e01 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7319,6 +7319,14 @@ class SharedFunctionInfo: public HeapObject {
   // a Code object or a BytecodeArray.
   inline AbstractCode* abstract_code();
 
+  // Tells whether or not this shared function info is interpreted.
+  //
+  // Note: function->IsInterpreted() does not necessarily return the same value
+  // as function->shared()->IsInterpreted() because the shared function info
+  // could tier up to baseline via a different function closure. The interpreter
+  // entry stub will "self-heal" this divergence when the function is executed.
+  inline bool IsInterpreted() const;
+
   inline void ReplaceCode(Code* code);
   inline bool HasBaselineCode() const;
 
@@ -8353,6 +8361,14 @@ class JSFunction: public JSObject {
   // Tells whether this function inlines the given shared function info.
   bool Inlines(SharedFunctionInfo* candidate);
 
+  // Tells whether or not this function is interpreted.
+  //
+  // Note: function->IsInterpreted() does not necessarily return the same value
+  // as function->shared()->IsInterpreted() because the shared function info
+  // could tier up to baseline via a different function closure. The interpreter
+  // entry stub will "self-heal" this divergence when the function is executed.
+  inline bool IsInterpreted();
+
   // Tells whether or not this function has been optimized.
   inline bool IsOptimized();