Experiment: assert for stack-allocated GarbageCollected<>s.

third_party/WebKit/Source/platform/heap/StackFrameDepth.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef StackFrameDepth_h
 #define StackFrameDepth_h
 
 #include "platform/PlatformExport.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
@@ skipping 33 matching lines @@
     {
 #if defined(ADDRESS_SANITIZER)
         // ASan adds extra stack usage leading to too noisy asserts.
         return true;
 #else
         return !isEnabled() || isSafeToRecurse();
 #endif
     }
 #endif
 
+    static bool isStackAddress(void* pointer)
+    {
+        uint8_t* address = reinterpret_cast<uint8_t*>(pointer);
+        uint8_t* stackBase = reinterpret_cast<uint8_t*>(getStackStart());
+        if (address > stackBase)
+            return false;
+        size_t stackSize = getUnderestimatedStackSize();
+        if (!stackSize)
+            return false;
+        return (address >= stackBase - stackSize);
+    }
+
     static size_t getUnderestimatedStackSize();
     static void* getStackStart();
 
 #if COMPILER(MSVC)
 // Ignore C4172: returning address of local variable or temporary: dummy. This
 // warning suppression has to go outside of the function to take effect.
 #pragma warning(push)
 #pragma warning(disable: 4172)
 #endif
     static uintptr_t currentStackFrame(const char* dummy = nullptr)
@@ skipping 41 matching lines @@
 
     ~StackFrameDepthScope()
     {
         StackFrameDepth::disableStackLimit();
     }
 };
 
 } // namespace blink
 
 #endif // StackFrameDepth_h