Fix leakage of virtual address space on Linux platform.

src/platform.h

Index: src/platform.h
diff --git a/src/platform.h b/src/platform.h
index 85901240f3d0740e86d1f6569710906e8754da1c..99deb1bef02394d97eaa2f687f10b16dbca8992b 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -351,12 +351,14 @@ class VirtualMemory {
 
   void Release() {
     ASSERT(IsReserved());
-    // Notice: Order is somportant here. The VirtualMemory object might live
+    // Notice: Order is important here. The VirtualMemory object might live
     // inside the allocated region.
     void* address = address_;
     size_t size = size_;
     Reset();
-    ReleaseRegion(address, size);
+    bool result = ReleaseRegion(address, size);
+    USE(result);
+    ASSERT(result);
   }
 
   // Assign control of the reserved region to a different VirtualMemory object.