Revert of [Oilpan] Set stack limit using estimated sizes (Re-land)

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index b2f2f607b8ffa5946229c83e6d037e7788824978..a552cc3bcace888a7640d578698db16cd19550bd 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -254,9 +254,7 @@
 
     if (isMainThread()) {
         s_mainThreadStackStart = reinterpret_cast<uintptr_t>(m_startOfStack) - sizeof(void*);
-        size_t underestimatedStackSize = StackFrameDepth::getUnderestimatedStackSize();
-        if (underestimatedStackSize > sizeof(void*))
-            s_mainThreadUnderestimatedStackSize = underestimatedStackSize - sizeof(void*);
+        s_mainThreadUnderestimatedStackSize = StackFrameDepth::getUnderestimatedStackSize() - sizeof(void*);
     }
 
     for (int heapIndex = 0; heapIndex < LargeObjectHeapIndex; heapIndex++)